Okay... so one thing you can do is probably be playful with him when he's here, over-acting the fact you're living together "for a while".

Also you could make a good dinner (complete with the dessert) on the day he works to surprise him when he gets back home.

As for organizing things... don't overstress that, you'll probably be able to come up with things on the fly. But maybe you should check to information points where you live for upcoming events or things to do. You could also wait until he arrives and do that with him so you can both decide what to do. It might even be better because you're implicating him.