Forget time of day, at least it should have a fairly consistent schedule! Last month, mine came the day I landed in another country on small school trip (with a cold, mind you... all of the unfortunate sneezing), lasted a week, and then CAME BACK just two weeks later to fall on my birthday. Because periods.
When I started having my period, it came like every 3 months. Went to the doc and got a prescription for birth control, since then it's super accurate. (I wasn't even sexually active yet)
Oh dang irregular ones suck, my friend had hers and it lasted two weeks then she had 2 days of freedom and it came back. The body is so weird sometimes
so mostly in school O-O
I wish that ^^ was not the truth