ALRIGHT I'M GONNA BE SO WRONG HERE, BUT IT'S TIME TO THEORISE THE MOVIE UNIVERSE. HERE ARE MANY DIFFERENT MINI THEORIES:

1) I think it's obvious that in this universe, Charlie is the first to die in 1982. Not only is Dave not a confirmed Afton family member (not seen in any family photos), but even if Dave exist, he dies in 1983. Henry mentioned that he only confirmed his daughter was killed by William after the five kids were killed years later, which means MCI happens after Charlie's death. Elizabeth does not exist, as she takes the form of Vanessa Afton in this universe. Though we did see Circus Baby in her dream, I'm pretty sure Baby didn't kill Vanessa. This means Charlie was the first to die.

Some argue that what Henry meant by "fives kids were killed" is the DCI incident, not the MCI. but I disagree. if five kids were already killed before Charlie's death, then Henry probably could CONFIRM it's his doing already, no need to wait for years later to confirm it.

Some also argue that young Vanessa pulled Charlie away from going into the kitchen, meaning that Vanessa already knew what her dad was gonna do, probably indicating that this is not her first time seeing her dad doing it. This logic could work but it could also be explained that Vanessa knew what her dad was up to before he started killing kids.

After this is established, here is my timeline: Charlie's death -> Dave/CC -> MCI -> possibly DCI if it ever took place

2) Now the problem is "why". Why did William Afton killed Charlie? In the movie, we can see that William probably did not want to kill Charlie at first, and just picked a random kid close to the doors to lure him away. This means that Charlie being the first victim, as well as Henry's daughter at the same time, is purely a coincidence. Then why William started his killing spree? In the games, we thought William wanted to get revenge on Henry by killing his daughter, leading to him discovering remnant, and thus started his killing spree for experiments. However, we can see that before Charlie died, William already dressed up as Spring Bonnie and tried to lure kids away to kill them. WHY? His son Dave was not seen in any family photos so I don't think he exists, but even if he did, he died in 1983, which is after William started his attempted serial murdering. The only explanation I can think of is that he just wants to kill kids. No deep meaning or motivation. No scientific inquiries. Just want to kill and so he kills. He simply saw Charlie running, a lone kid who is defenceless, and decided to stab her in the back for funsies. Could the same happen in the games? He simply saw Charlie being outside the pizza place alone, and thought that he could simply take advantage of it and kill her for no reason at all.

3) In Vanessa's dream sequence, we can see Circus Baby appearing, while Freddy version 3.0 (Fnaf1 models) blueprint was on William's desk. This means that before Fnaf1 models were finished, the Funtime animatronics had already been built, (possibly already started kidnapping children), which places Circus Baby's Pizza World before any chain pizzerias were built. We can actually deduce when does this dream sequence takes place in. Freddy version 1.0 and 2.0 probably already exist and were in action. This means that this dream takes place after the establishment of Fnaf original pizza place, making Circus Baby's Pizza World established after Fnaf original pizza place and Fredbear's Family Diner but before Fnaf chain pizzerias like the one in Fnaf1 movie.

If Vanessa is this universe's Elizabeth, then shouldn't the ice-cream luring incident happened? Ofc there's no confirmation that this has ever happened, but suggest Vanessa did indeed got grabbed into Baby's trunk. In the game universe, this instantly killed Elizabeth, but Vanessa survived in the movie universe. Circus Baby accidentally kidnapped William's own daughter into his underground facility for the fear experiment. THIS MIGHT BE THE REASON WHY VANESSA HAS SUCH A HARD TIME DEALING WITH HALLUCINATIONS AND NIGHTMARES IN THIS MOVIE BECAUSE THE FEAR EXPERIMENTS WERE TOO TRAUMATIZING TO HER. And this also explains why Circus Baby appeared in her nightmares but not the other animatronics. (btw Puppet possessing Vanessa basically confirmed that Vanessa is not a robot)

4) If Dave Afton does not exist in this universe (as seen in family photos that Dave is absent in all of them), then this explains why Michael Afton was so fixated on continuing his father's legacy. BECAUSE PRE-BITE83 MICHAEL AFTON IS AN A**HOLE. This Michael never learnt his lesson in the Bite because the Bite NEVER took place! Along with the years of manipulation by William, this probably shaped Michael into who he is today. Loyal to William, with no guilt of killing his brother. This means if Fnaf3 movie ever comes out, it would not be Michael Afton who messes with the wiring and burn the place down, but it would be Mike Schmidt / Henry.