My LQS will hold for a regular customer for about a week, longer depending on how much of a regular you are. They will cut the yardage and set aside. I have seen a few ask for a credit card number in order to "hold" the fabric and charge it as sold the day it is cut , its up to you then to get there to pick up an item you already paid for.
Others that do not "know" me all that well, will tell me anywhere between 24 - 48 hrs. Often when I go in to pick up.. they have the bolt next to or on the counter with a note reverving the amount. So that customers can still see/purchase from the bolt.