So what's the actual difference from last year except that we probably don't have to go to the store because of the mail in trade in? This thread started with a strange question about how the IUP works and I'm confused as to why since there shouldn't be a question about the basics.
You go to the IUP page in the app and say you want to upgrade your phone. As was said, you can test that today and it's the same except the only thing there is the iPhone 7 options.
Friday you will have (we assume) the 8/8 plus/X options.
We hope we will just order what we want and it will be shipped to our home address, a lot simpler than last year!