Probably a few days at the least. I dunno, I always get mine back the same day, but I also always pay in beer.
Or you could not be a pussy, grab some duct tape, a pen, a drill and a screwdriver and do it yo-self. I've mounted two pairs of skis on my own and both have been dandy. Those were acts of necessity and I prefer to get it properly done if possible(risk aversion, but even shops fuck up), but my mount skills were evidently up to task with the rudimentary equipment I had.
Tape your bindings to you skis where you want them; you can either mark the spots with a marker or drill through the binding screw holes, depends on your binding/drill. Check out the depth of the ski/screw and duct tape around your drill bit to that depth so you don't exceed it. Don't want to go all the way through. Drill said holes. Screw in bindings. It's pretty easy actually. The only value shops add is the mount jigs and the screw bits that taper to the correct depth. Both those you can easily jimmy-rig. If I had a monkey, I would train him to do it for me.
Anyone else ever mount their own skis?