The following attempts to lay out both timelines of what happened in Taldou on May 25, drawing on both alleged witnesses with a general government/Shabiha attack narrative and those with a general rebel attack narrative and then video evidence, for comparison purposes. (slightly incomplete at the moment, but getting there)
Video Timing note (2016): This page has long reflected a bad understanding of the time zone. The proper calculations will use time zone GMT +2, with daylight saving time on. Previously, GMT+3 was used. Sunset is 7:38 pm, not 8:38. The table below is now updated, with timed videos shifted down an hour, around 1:30 pm, 6:10pm, 7:30pm.
Before the attack/earlier in the day
The version of events related by those blaming the government include consistent features of the period before the government forces invaded. Friday prayers, a planned Friday protest, an impromptu fight at a checkpoint (or several), and a shelling attack The following events do not have specific times attached.
- Protest, then fight, then shelling: The Daily Mail heard “There had been a protest earlier in the day which led to an exchange of fire at an army checkpoint at Taldou on the outskirts of Houla. Later there was shelling." 
- Fight, then shelling with no protest: Martin Chulov heard: "Around mid-morning in the village of Taldou, on the outskirts of Houla, they knelt in the streets for prayers, half an hour of piety and reflection before a weekly ritual of rage and defiance. But the placards were never used," as the shelling started, at 1:15. “According to several accounts, the Shabiha and regime troops [had] rallied after members of the Free Syria Army attacked a checkpoint earlier in the day.” 
- Protest, then shelling, then fights: Der Spiegel heard "After Friday prayers on May 25, the residents of Taldou formed their usual protest marches against the regime. But then, in the early afternoon, army forces began heavily bombarding the village from several surrounding bases. FSA units launched counter-attacks on a number of army checkpoints." 
The version of events related by those blaming rebel attackers include consistent features of the period before the government forces invaded. a coordinated rebel assault on numerous security check-points, some decisively taken, the use of mortars and/or RPGs and heavy machine guns, and attacks on certain homes. Other details vary greatly, based on what portion of the events they witnessed. Most of these accounts seem to include information they gathered from others rather than witnessing themselves. Since their checkpoint skirmishes are more connected to the invasion/attack, and are given times beyond 'earlier in the day,' they will be included below.
Otherwise there is little information for what happened prior to that in the alleged rebel attack. One alleged rebel fighter, since surrendered to the authorities and reporting his view, ('the rebel insider" here) reported one event prior even to the day. "'"[He] said that he used to accompany the gunmen and knew the details of their work, and that three days before the massacre, the gunmen had been discussing something that would happen on Friday, saying that it was something "special and big."" On the 25th “after the prayers, a unit of the fighters gathered in the northern district … beyond the checkpoint, next to the place with the clock.” He himself was with a side-group on Tripoli Street, he says. (insider)
|Combined Timeline of Events|
|Time (est)||Witnesses for Government attack||Witnesses for Rebel Attack||Other (mostly video)|
Solar noon: 1:31 PM local time.
|1:15 - Just after prayers, the first artillery shots pre-empt the protests; continued shelling prevents men from returning home to protect their families as splinters flew. (Chulov June 1)||"Jibril" reported “The fighting began around noon, when the rebels, coming from Ar-Rastan and Saan, attacked the checkpoints of the army around Hula. ("Jibril")||Some rebels seen running around side-streets with rocket launchers |
|1:30/2:00 forward||Government shelling started, before or after protests and/or minor clashes||Events started with Nidal Bakour's group firing from the NW at "the checkpoint" at the clock tower, around 2 pm after the friday prayers. One rebel named Okesh fired a mortar at them, and was shot down. ("Arifah") The SANA summary says it was around 1:30 when they "attacked checkpoints in the area simultaneously" and "kept attacking for nearly three hours..." (SANA)||1:25, +/- 15 min: Rebel shooters seen northwest of clocktower, firing machine guns towards the checkpoint - one is shot down, badly wounded. (explained)|
|By 4 pm||Chulov: “Sometime between 3.30 pm and 4 pm, according to locals, the shelling eased. There was, however, to be no reprieve. Witnesses say the Shabiha gathered near the water plant and the military depot nearby.” ||"Shortly after” their first attacks, Al-Hallak’s group also attacked “another checkpoint … located at the mountain. ... At around 3:30 pm” ("Arifah") This might refer instead to the hospital post; "the first thing that was overrun.” ("Jibril") They stole the weapons, executed two soldiers, and set fire to the checkpoint along with the "nearby hospital" ("Arifah")|
(up to sunset)
|Combined Timeline of Events|
|Time (est)||Witnesses for Government attack||Witnesses for Rebel attack||Other (mostly video)|
|2:30||Akrama Bakour told the BBC the killings down Saad Street began at 2:30 PM. No other accounts go this early.|
|4:30||Fighters passing north as early as 4:30 from the dam area, whose inhabitants were “among the frst to be killed”  Maryam Al-Sayed: "at around 4:30 pm a group of soldiers passed (the Muawiya Al-Sayed family's) house coming from the waterworks in the south and banged on the door … they did not open the door.” |
|5:30||Defector Jihad Raslan: "At 5:30 am [sic] I saw the security and military forces … They came from the city’s Mussasat Al-Miyah district and headed towards Sadd [sic] street … After 5:30 pm families headed west of my house." |
|6:00||“At about 6 p.m., we heard a tank on the street and men on a car who were chanting: 'Shabiha forever! With our blood and our souls, we sacrifice ourselves for you, oh Bashar!' We had never heard that before." ||At the place overrun at 3:30 - “I didn’t see them burn him, but I heard them howling that they burned a soldier, that was around 6:00 pm.” ("Arifah")|
|6:30||A survivor told the BBC "At about 18:30 we heard gunshots. I was in a room by myself when I heard the sound of a man. He was shouting and yelling at my family. I hid behind the door... They were wearing military clothes," and killed her family members. 
Malik Baqur says, in his full Spiegel interview he reached the massacre site at 6:30 after walking from elsewhere. He saw 40 of the attackers "about 150 meters from the homes of the residents" that were leaving "in the direction of Fullah" with a silver armed truck. He watched them march away in that direction for ten minutes. 
|5:35 +/- 25 min: video filmed from far to the north catches smoke pouring from the clocktower area and miltary intel (MIHQ)|
|4:00-7:00||4 pm to 7pm: Apparent Lull in the fighting between opposition and security forces, by most accounts. Instead, the killing inside households of the Abdul Razak family, on Saad street near the water plant and the hospital, commence. The UN's CoI frst heard that “by most accounts the killings on Saad occurred between 16:00 and 18:00.” (p. 8)||1:30-6:10 pm: no (published) opposition videos filmed in Taldou.|
|7:00-7:30||"About 7pm armed Shabiha, the pro-government militia, some of them possibly coming from the Alawite villages that surround Houla, swept in and the massacre began."  - Civilians running away continued to 7:00 on Saad street, Raslan reported, and he checked some houses with a flashlight "a half hour later" (sunset, 8:36 pm).||At 7:00pm Al-Farouq brigade, led by Abdulrazak Tlass, of the so-called “Free Syrian Army” arrived, with 250 fighters from Rastan, along with other sizable groups, takes check point at the mosque, perhaps the one near the clock tower in Taldou's north-center. ("Arifah")||6:11, +/- 5 min: Apparent rebel seen firing multiple RPGs on north Saad street, near city center. Three dead men and a fourth man are scooped up by rebels into a black van and driven south. (explained)|
|Chulov: "By early evening, much of the killing had stopped, the witnesses say. According to the residents of Houla, most of the militiamen had returned to Foulah and Qabou. A small group, however, remained behind." ||By 8 pm, the bodies from the day's fighting had been gathered by the armed rebels, and been trucked to "the mosque." (anonymous) This is apparently in the north of town, perhaps the same mosque by the checkpoint.||7:19 +/- 4 min: gray smoke drifting over hospital. App. 7:30 a rebel unit seen firing RPGs south down Main from Satto Road (explained) App 7:30 Apparent RPG firing on the hillside west of there, towards the "water company" (explained) - 7:40 +/- 7 min: Another video shows rebels shooting machine guns down Main Street just past sunset, by the overrun MIHQ, towards the Qaws (arches), and smoke rising from the hospital (explained)|
|Combined Timeline of Events|
|Time||Witnesses for Government attack||Witnesses for Rebel attack||Video/Other|
|10 pm-4 am||Reuter, Spiegel: "[T]here was another wave in another part of Taldou between about 11 p.m. and 4 a.m. Because it was dark by then, none of the survivors saw where the killers had come from. But given that the houses were between two army checkpoints, it would have been almost impossible for rebels to move easily from house to house and shoot the residents without clashing with soldiers." ||Rebels occupy southern district of Taldou and kill Alawite families, then took all bodies to the mosque. (anonymous)|
|unstated||Various night-time videos show massacre victims in rebel custody gathered into groups in unknown rooms, then as the mosque in the north of town.|
|11 pm||Attack on Muawiya Al-Sayyid’s family by the hospital, per Maryam. "At about 11 p.m., we could hear voices through loudspeakers, saying: 'All lights out! Including candles!'" Soon they entered and started killing, but most inhabitants fled. 
Ali Al-Sayed, at another house, has a close call: "I heard voices outside at about 11 p.m. 'Turn off the light! Open the door!' they said. But the electricity was off, anyway. I heard them hitting the bottom of the door, but then they left.” 
|3/4 am||Attack on Ali Al-Sayed's home: Chulov: "A small group [of Shabiha] remained behind. It is this group which is believed to have gone looking for the Sayed family at about 3am on Saturday morning." 
Ali to Spiegel: "I woke up again just before 4 a.m., when men came into the house. My brother and I were lying in the living room. When my sister Rasha tried to run away, one of the men shot her…” 
|Early Morning||After the killing and looting, a spared Ali runs to an uncle's house, where he witnesses Shaniha arrive and ask his uncle who that was they just killed. That uncle later came on Syrian state TV, blaming "armed gangs" (see Ali Al-Sayed)||Government forces regain control of the southern stretch of town and Sayed massacre sites by early morning the 26th, it seems, and are present to escort UN monitors into town.|
International Committee of the Red Cross (ICRC) reports on June 1: "Fearing for their lives, thousands fled the village while the fighting raged and took refuge in Burj al-Qa'i, a village some five kilometres east of Taldaw, and in other nearby villages. "People left everything behind as they ran for their lives," said Marianne Gasser, the head of the ICRC delegation in Syria. "Most of the displaced are women and children." Burj al-Qa'i is a village in Houla plain with barely 1,000 residents. Overnight, it found itself hosting 5,000 people who had fled Taldaw in search of safety. "Many of those who took refuge in Burj al-Qa'i ended up in schools and other public buildings, others with host families," said Ms Gasser. "There was not enough food, water and medicine for everyone, which put a great deal of pressure on the small village." Both the ICRC and the Syrian Arab Red Crescent went to Houla plain this week. They provided food, water, mattresses, baby milk, medicines and other items for the displaced in Burj al-Qa'i. In addition, they installed and filled water tanks in schools and other places where displaced people are taking shelter. Some of the people who did not manage to go to Burj al-Qa'i or elsewhere stayed behind because they were injured. A team of Syrian Arab Red Crescent volunteers and six doctors headed to Taldaw immediately after the events, treated dozens of people on the spot and transferred several to a hospital in Homs city."
- As the world dithers over Syria, shocking evidence of an entire family massacred by Assad thugs: Father finds his wife and five children among the victims of the Houla atrocity By Nabila Ramdani and Ian Gallagher. The Daily Mail, June 9, 2012.
- Martin Chulov for the Guradian, June 1, 2012. The Houla massacre: reconstructing the events of 25 May
- Christoph Reuter and Abd al-Kadher Adhun for DER SPIEGEL, "Searching for the Truth Behind the Houla Massacre", published July 23, 2012, video interviews
- Youtube video: ةلولا يطشانلادحا فصي ام ثدحي فصقلاو رمتسم 25-5-2012 - “Hula (??) describes what is happening and constant bombardment” - 5:33 (rep) Published May 25, 2012 by Monther Hrfosh.
- Houla: How a massacre unfolded BBC News, June 8, 2012.
- "Syria: The Tipping Point" Martin Fletcher reports on a war crime in Syria. The Times, May 30, 2012.
- Syria: thousands of displaced in Houla need urgent help, ICRC, June 1, 2012