I would agree with the others that inviting him to move in so soon is bad juju. You know little about him, and he spent the night that soon. While hardly unheard of, right now I think you're both feeling a bit of infatuation. That is going to cloud your judgment, so take it slow and get to know him. You might find him spending an awful lot of time at the house, but you really need to learn who the person is behind everything to know how well (or how long) this might work out.
My wife and I are in a similar situation though, and when I can find a spare hour or six to chronicle our lives over the last several months, I'll toss my story in the ring as well to get some input and hopefully a little understanding of my own about what we've found ourselves in the middle of.