When does time start and when do I split each boss and when does time end.

We answered you on stream but just in-case anyone else needs to see it: Launch the timer after the intro finishes stop timer when you kill The Soul

For future reference, most games have the rules for starting and ending in "View Rules" on the category/run page:

You can split whenever you want. I personally use the auto-splitter, zic3 splits when the soul combines with the player, some people split when they touch the floor or leave the arenas. It's up to you.