Depends, usually between the second and fifth date. My rules are never on the first date and if by date 5 we havent had sex then i move on. The norm is date 2 or 3 though.
I don't see anything wrong with sex on the first date as long as you're doing it for the right reasons. If it's two grown adults then why not! Only childish men use a woman for real.
As few as possible.
I'm a horny bunny so if there's chemistry and my panties are wet why wait?