Due to personal reasons and schedule, I will have my first opportunity to buy the new iPhone on Saturday or Sunday. I have never purchased an iPhone before. With all of you guys having experience in the past buying iPhones when they first come out, am I going to have a problem find places like the Apple Store or Walmart having them in-stock? Are these things really going to be sold out? If so, how soon might they get more stock of them in? Thanks!