When you're independent.
For example, moving away from home,
Doing your own bills, laundry, stuff like that..
I suppose it could also be at the loss of virginity or the turning of 18 but I don't agree with these,
Having completed one of those criteria without receiving the self-considered title of "Adult".
Wait, what's the plural of "criteria"?
Is it just Criteria? x.x
Or is Criteria the plural and there's a singular word for it...?
Gosh, I ain't such goods @ Unglesh