Just called my local Apple store about in-store reservation. It is a guaranteed item, but ONLY for that day 6/19. I asked to see if my name was in their system and they looked it up and told me everything. They clarified my name, told me my upgrade fee, and what my price would be and my iPhone model and color that I would be purchasing. They said that I can come in any time between their store hours and I still have to wait in line though. However, he pointed out that it depends on what length of line you want to wait in and advised me to come later in the day as lines get shorter. But, I'm still coming there at 4AM just for the moment. So, this is excellent news for anyone that thought the in-store reservation was a waste!