if you have paid for it, they will hold onto it with your name for awhile. In fact, I've had them call me after I didn't pick up an order after 10 days or so as I was out of the country. As long as they know you intend to pick it up, most of the time they'll hold it.
I'm not sure is this is a store-by-store policy or not though. If you intend to pick it up within a week or so, you'll be fine. longer than that, just give the store a call after you place the order.