I’m in the “do it when it feels right for both of you” camp. Strangest situation ever:- good friends for four years. Then mind blowing sex out of the blue. Followed by three years of steady going out. And now it’s back to very good freinds.
Current situation:- dating for just a litlle while. Then I wanted sex, she said no. Then she wanted sex, but I said no. Presently in the mind blowing sex stage 
OK, just an update based on personal experience…
I just got married 3 weeks ago. As you may recall, my wife and I were both in the “no sex before marriage” camp. A number of people felt it was stupid to enter into a legally binding contract without checking the merchandise first, as it were, and the question was asked, “what happens if you get married and the sex is bad?”
Well, before we got married, my [then] girlfriend and I really enjoyed cuddling, snuggling and kissing. Now that we are married, we still cuddle, snuggle and kiss. The difference is that we take a break and have sex (which is very enjoyable, by the way!) and then go back to the cuddling, snuggling and kissing.
We both work busy schedules, and there have been nights when one or both of us simply do not have the energy to “go all the way” (I had no idea that sex could be such a physical workout!) On those nights, we simply cuddle, snuggle and kiss without having sex.
I don’t love her any more (meaning to a greater degree) now that we are regularly having sex, and I don’t love her any less on the nights when we don’t have sex. In short, although we now do incredibly enjoyable things together that we didn’t do before, the essential nature of our relationship has not changed.
Just thoiught I’d share that…
Regards,
Barry