I want to buy a new MBP this summer, but I'd prefer to wait until the new ones come out. However, I do need to get it before Aug 17th. Let's say they haven't released the new MBPs by then and I buy a new one on the 17th. If a new model comes out the next day, I know I can return it and get the new model for free. How long is this "upgrade insurance" in effect for? 14 days? 30 days?