In my own experience, waiting for folks to check in is the HARDEST part of this whole gig. I have learned that it is okay to:
-reconfirm by email or phone their real travel plans (some folks booked months ago, and don't even remember what they said)
-go about my business a little bit and be outside planting plants, or mowing the yard, or whatever else needs done, as long as I've got an eye out for them
-or actually leave a key and a letter (after talking with them by phone and learning that their real plans have nothing to do with the plans they said when they booked.) I actually thank all the members of this forum for getting me to this point. Just today I had some guests who were actually relieved when I offered to leave a key and a letter outside so they didn't have to sweat the time, and I didn't have to hang around. Win/win for both of us! Thanks everyone! (But I still have to admit, I was relieved when I happened to be around when they arrived, so that I could personally greet them and show them around. I do think it makes a difference).
But truly, of ALL the hard jobs innkeeping entails, waiting for late check-ins is the abolute hardest.