Another thing to consider. Are you guys humping ladders around, bakers scaffolds, or lifts? If this place is any sort of retail, grocercy, or high traffic business, there WILL be stuff in the way. That can slow your pace quite a bit. Will there be people working or shopping? Try to do it at night if you can, this takes a lot of the hassels away.
Remember - Repetition and speed is where your money is. The first one is always slower cause you haven't got your rhythm yet and your figuring out all the kinks.