He might have either gone to the tavern or to the cottage in the forest depending on which one he is doing, if you can't find him in the shop, he will be in one of those places at night.
No problem, those are the places he can go to at night when he is not in his shop, if he mention that he is going to the tavern for a drink, then he will be in there at night in the town, on Friday, he will be in the cottage in the forest.
