For me, losing virginity was always AS SOON AS POSSIBLE, and still took until I was 17, for reasons completely out of my control. All in all it wasn't too much later than I expected it to be, marriage issue aside.
An advantage of a Talmudic education (that my Rabbis wished I never realized) was that I was able to find loopholes, justifications, and counter-arguments for everything - and my hormones gave me a reason to find them.
My mindset was always "as soon as possible." Although growing up I made sure I took precautions (like making sure I had a condom handy). Lost my virginity at 17 and I had absolutely no moral hang ups about it. IMO, waiting for marriage to have sex is a dated concept.
1) I was raised very religious and therefore legitimately thought I would stay celibate until marriage.
2) I still managed to lose my virginity at a very young age.
3) I have regretted losing my innocence too early and maturing too fast for pretty much the rest of my life.
I suppose I should clarify a couple more things for myself. I was not raised very religious. And while I did not have moral hang ups about losing my virginity at a young age, I wasn't out there trying to bang any chick that would have me. I saved it for a girl who I cared deeply for. I've moved on from her and currently have no moral hang ups of having a friends with benefits situation at the moment.
I smoked a spliff, drunk roughly 10 beers, got my usually over excitable penis out and attempted to plunge it into my willing lady friend and only to realise I wasn't particularly standing to attention.
A freezing cold blow job later, I had sex for the first time.
I left very disappointed. I presume most people felt that way after the first time. The hype was way higher in my head, and I have happily gone on to realise those particular dreams.
EDIT - Not religious. Turned down sex a couple times beforehand. The girl was a long time friend that I knew had always wanted to get me in her. Not a bad thought about how it went down, I was just happy at the time to get it out of the way.
My first time having sex was actually great, and it went quite well (in terms of the girl being satisfied). However, my first time was with a girl who was cheating on her boyfriend with me. I regret that now with hindsight because I've been cheated on, and I've also cheated on somebody, but those were always strong beliefs of mine growing up. That I wouldn't tolerate unfaithfulness, and thus I would remain faithful or get out of the relationship. Sadly it didn't take much for neither of those things to be true. Though I have been with my current girlfriend for about 3 years now and haven't cheated on her, and I cheated on a different girl with my current (ex at the time) girl. Sloppy situation, but it is what it is.