When I had to exchange my MBP within the 14-day warranty window, the Apple store I went to held the replacement from ~3 in the afternoon of a Thursday until noon the next day when I was able to get down there (~1 1/2 hour drive to Boulder, CO from here). I was thrilled they did that since I wouldn't want to drive 3 hours round-trip and not come home with a new machine and since MBP's were/still are flying off the shelves especially since they could, without doubt, have sold that same computer a couple times over in the meantime.