Technically Rev. Chuck is correct. Unless something is seriously wrong 30 minutes to an hour is all it should take. However, there are other factors to consider. One is how busy the shop is. Another is how much they value you as a customer.

From the shop that I've bought two Specialized mountain bikes they have done this type of work while I waited. They were happy to let me watch and answer questions and are willing to point out things for me to check for on my own.

From the shop that I bought my Litespeed road bike the jackass owner promised me that my 30 day checkup would be done by the next day. Five days later and after repeatedly being told on the phone that they were just too busy I walked in and surprised them while they were all sitting on their butts drinking. They were no other bikes on the bike stands that they were working on.