So in my case I have the 7 plus and want to preorder the X on launch night. I still have a balance of over 300$ on my 7 plus but am planning on trading in my 7 plus. However, I want to use the Apple Store app to preorder because it's the fastest and simplest way and each time I've ordered my 6 plus, watch, and 7 plus I managed a launch day delivery. How will it work for me cause I'll need to trade in my phone after i get the X and will buying it off the apple store app without trading in my 7 plus be a problem seeing as I'm not doing it through AT&T directly? I just wanna make sure I do it right and get my phone quickly without issues.