That is a good question; without a way to keep track of time, they can't really arrange meetings.

"Well, you told me where you live, didn't you? I can knock on your door or leave you a note when it's time."

That's about the best he can think of, short of them just being metaphorically glued at the hip, which he's sure doesn't sound any more appealing to her than to him. For Sam in particular, he is a charismatic, outgoing introvert, but still an introvert, and needs his alone time.