When is the right time?

Ive been kind of dating this guy for almost 6 months now and we're in love I believe. We both go to church regularly and our families know each other and get along. He's 21 and I'm 17 I turn 18 in a month and few weeks. I'm about to start college soon and so is he. We're in pretty good places in our lives right now and have great compatibility. Only thing I'm thinking about is when is it okay for us to have sex? I wanted to for awhile just wait and see if we'll get married but I do want to do it. I've had sex before with different men so it's nothing new and same for him with women. I just want this to be different than any relationship I've been in and it feels right I just want to be sure. Any ideas?