It totally depends on the size of the booth ( a 6 foot table versus a full 10x10 corner booth), the distance for parking/loading and ease (load in can suck up a bunch of time), whether the show is indoor or outdoor, and how complex I decide my set up will be.
If I spend time before the show, tagging and pricing stock and pre-pinning my jewellery displays, then I need less set up time at the show.
So an hour would be the minimum for a small space, when I've got everything pre-pinned, priced and organized, with an easy load in. 4-6 hours would be the maximum.
At a show two years ago I had to wait in line for an hour just to be able to drive in and unload! It was winter and the load in was in basement level of the complex, only about 4-5 vehicles at a time could drive in at a time and it really wasn't feasible to pull my stock and displays through the snow and down a very sharp icy ramp.