>>522
There's plenty more problems than that.
The "pre-war" bit is something we have no canon information for, so it shouldn't even be included. Our knowledge starts with the war between humans and monsters, and goes from there; for all we know, war might have started as soon as either humans or monsters came into existence.
The time that the "war" lasts should be very little; possibly only a few days because the monsters were decimated. Between the monsters being sealed and Asriel being born should probably be thousands of years, also.
There shouldn't be any space between Chara and Asriel's death; that happened on the same day.
There's nothing to suggest when Gaster died except that it was before the events of the game, although presumably the CORE was finished before Asriel was born, otherwise they wouldn't have electricity in New Home, so why would it have lamps?
There was not that much time between Asriel's death and Flowey being born. Probably about a year, because the flower that bloomed on his grave came from a seed. The time Flowey was fucking around with the timeline also could have been centuries. There's no indication for how long it took the other 6 humans to fall in.
Frisk's Determination would have overridden Flowey's as soon as he fell into the Underground.
There's some pretty good evidence to suggest that the events of the game take place during a single calendar day.
The split from the Neutral and Pacifist timeline should be much earlier, in fact before the death of Asgore — right after sparing Mettaton is the correct place. It needs to reflect the fact that either confrontation with Asgore takes place at the same time.
Frisk cannot have left the Underground in Neutral because he didn't have any SOUL other than his own.
The Genocide looping onto itself makes no sense, because you can do a Neutral or Pacifist (well, Spoiled Pacifist) run after a Genocide run; it should loop back to Neutral just as the Neutral line does.