Like Princess said above, my hubby and I have been together since we were 16. Well, he was 17, whatever. xD I'm now 25. So we always had a general idea of how we wanted life to pan out - graduate college, get married, enjoy that a few years then start a family.
We're coming upon 3 years of marriage in September, and my sister had her first baby in December. Not long after she had him, I knew we were getting hooked, so we sat down and worked out a timeline. I said, "you know, we both would like to start a family in the future, could we figure out a timeline so I can mentally prepare for doctor's appointments, read up, etc?" And he was more than willing. That was about 6 or so months ago, and we'll be TTC in June.
You know your OH best, but I figured that a gentle, "let's do this together" approach would work best for my hubby. And it did. He was grateful I came to him rather than just offed the pill and told him, "Hi, we're expecting," like a friend of ours did. So we talked it over casually and then formally and now we're both looking forward to the baby-to-hopefully-come-soon.
Best of luck! xo