With my first boyfriend (when I was a virgin) I was dating him for three months before having sex with him. I'd have probably slept with him earlier if he'd asked, to be honest, it's just we were both panifully shy and it took us a lot of guts to broach the subject.
One guy I felt pressurised into sleeping with after dating for two weeks because he suggested it and I figured the reason I didn't want to was that I wasn't over another guy so I should just push through it. That was stupid of me, I shouldn't even have been dating him because I was totally on the rebound, I realised that too late and after sleeping with him I dumped him the next time I saw him. o.o
With the two other guys I've been with, I'd been friends with and had a crush on them for ages already, so I basically slept with them as soon as I could seduce them. Those two are the only two out of the four that I don't regret being with (and one being my current boyfriend so I should hope so for him at least

).
Well, okay, I don't really regret losing my virginity to my first boyfriend because he used to be really sweet, but later on he turned into kind of a pig so that sorta sucked.