I am going to be switching from AT&T to T-Mobile and I had to order my iPhone7+. I am going to be receiving it this week. I am going to need to trade in my current AT&T iPhone 6+. What should I do to the 6+ before I trade it in to T-Mobile? I have performed an iCloud backup recently of my current phone. When I receive the new phone I think I am going to set it up as a new phone when I get it. What is the best way to get just my contacts back and not all the apps?