My local Apple Store is in a mall and if I had to give it a 1-10 scale on traffic I would say around a 6.
I have talked extensively with them and with the mall management and the mall will open it's doors at 6am for a line to begin forming outside the Apple store for the 8am release. They did, however, say that during previous releases they have done this as well and a line has formed outside the mall before 6, the line that forms outside the mall is maintained when moving to the Apple Store by security personnel.
The people at the mall and Apple Store recommended getting to the mall around 4-5am for a good chance at getting my hands on a phone since I hadn't pre-ordered.
I am not sure about your store but I hope this info helps you out.