Hi AnnJazz
It’s very variable. Sometimes hogs don’t move in until a box has become ‘part of the furniture’ and other times one will move in quite quickly. But some might just stay for a few nights before moving on elsewhere and others might stay longer. Some might only use a hog house for naps between snacks and have a day nest elsewhere, but a female might move in and produce her young there.
I would be inclined to put a small amount of bedding into the house, to give them the idea, but leave a nice supply of potential bedding nearby. Many hogs like to do their own interior decorations and some have even been known to remove all the materials a person has kindly put in boxes for them!
Good luck. I hope you get a tenant soon (assuming you already have a hog house). Happy hog watching.