There is usually no need for the animal to soak once the enclosure has been treated correctly with Provent-a-Mite. They still might do it, so it should be considered when giving a water bowl.
The one other thing I do is always pre-treat a plastic shoebox or sweater box (depending on the size of the snake) and place the mite covered snake in the box while I treat their cage and wait for it to dry. Doing this, I find that quite a few of the mites are killed before I even get them back to their cage.
Thor26, if you order from the Bean Farm, you'll most likely have it the next day. If you're close to them you can also call and just go pick it up.