To me, being boyfriends means that I'm required to do, all the stupid crap he might want me to do. Like.. I'm just expected to do something with him on his birthday. Make it a point to spend some of the holidays with his family, and invite him to do the same with mine, on the others. If he REALLY wants me to go see a movie with him.. no matter how much I think the previews sucked.. I should still go.
See.. when you're just 'dating'.. you have the OPTION of doing, or not doing, certain activities with the guy. Once you're the boyfriend I think by large that goes away.
Honestly.. if you like the guy, then you're probably already doing most of this crap. So it's not going to be a big change for you. For some folks, their expectations run deeper. Others really could care less.
When the moment comes you think you might be ready, just ask him... "how would things change between us, if I were to ask you to be my boyfriend?"