Really depends on a few factors...mainly weather, what type clear, and how many coats. If you just had to spot and clear something, normally a couple days. If you did a candy job that would include 10+ coats (sealer, base, graphics, clear...), you should wait at least 3-4 days.
My rule of thumb is, if it's a full paint job and I finish it after Wednesday, I let it sit through the weekend before packing and shipping.