I phoned the Westmont, Illinois Tesla store last week. A sales agent assured me that by retaining my Model 3 reservation, I would have priority over anyone in our region placing an order with my same configuration but without a reservation. Today I phoned the Highland Park, Illinois Tesla store and a sales agent verified the earlier information. Of course if that other person's order goes into the production queue, then I could not bump him/her by placing an order afterward. But when Tesla announces that orders for the smaller battery packs are being accepted, the priority given to those with $1000 reservations could make a huge difference in delivery times.