I think it would be a good idea to add a level leaderboard to the game.
How it works: So, there are act selects, you would just use each act as a level, then when you finish that act, you stop the timer.
Beginning each act is easy, since all you have to do is start when you start the act you want to do, though I don't know the end to each act.
Here are my suggestions
Intro: end when you reach the desktop
Act 1: end when the sound effect of the machine shutting down starts to play
Act 2: end when the screen is entirely black
Act 3: end when you press the start in recovery mode button
Finale: end when the screen is entirely white
Intro:End when you reach the desktop Act 1:When the screen turns completely black Act 2:When the screen fades completely to black Act 3:End when you press recovery mode button Finale:Basically pointless
Yeah I don't think there are going to be any other opinions on when the end should be. Just use Jarvis' idea for the end times it doesn't really matter a whole lot.
As of yesterday, a Level Leaderboard is now a feature for Pony Island on speedrun.com, featuring the acts in the game's NG+ Act Select. A full game savefile is available in resources for your IL needs!