For the age, seventeen! Chef from South Park says, "You know you're ready, when you're seventeen." As for regretting a sexual experience (that doesn't end in pregnancy or getting an STD), that's stupid. It's a learning experience. The first time you do it won't be near as good as after you've done it many times, so instead of regretting, think of it as a practice that builds on itself.
"Sex is like oxygen: it's not a big deal, unless you aren't getting any." -hahaha so good.
On the other hand, however, people who want to wait until marriage to have sex might be on to something. I was talking to my boss who is a strict Muslim. He and his wife were compelled to wait until marriage. It must be something about not having had a previous partner, because they still do it all the time. Not saying that the sexually exploratory among us won't continue to have great and frequent sex with a married lover years down the road, but it seems much more sacred if you keep the same partner your whole life. Not that I would know! Anyone here married to their only partner?