I think what you need to do is sit down with him and just tell him.
Such as, " I don't really know how you feel about this, but I really Love you. I don't really expect you to feel the same way right away, and I don't want you to run away. I just want you to know how I feel about you, I hope you understand."
Hopefully this gives you an idea. I think it depends on both people how they feel. I heard a co-worker say they won't say it until their a year or two in dating. To me that's almost for ever. I guess I said it too early after one month of dating. But I'm still with the girl, and its almost 9months now that we have been together.
Hopefully this gives you an idea of what to do.