Members of the iPhone Upgrade Program can get a "start" when upgrading to an iPhone X

Previews for the iPhone X begin October 27, and supplies should be limited. If you are a member of the iPhone Upgrade Program, you may have the chance to expedite the ordering process when the pre-orders begin.

Apple announced that program members could have an advantage in the ordering process on Monday, October 23. The banner indicates members of the Apple Store app so they "can speed up at checkout at 10.27".

This does not mean that IUP members are jumping the line, but getting members through the program loan eligibility process. That should allow these members to streamline their payment process on Friday, eliminating a few steps ahead of time. 9 to 5Mac notes that this seems only to apply to existing members and does not "necessarily warrant the launch day inventory".