I would wait it out if I were you. I have done this route before and have always gotten my upgrades as an EXP and a PLAT. They usualyl don't clear until the 24-36 hour timeframe so just be patient. Of course you could risk it, and it is a long flight definitely worth the mileage upgrade. Regardless of what you decide to do, make sure to check in at the 24 hour mark to maximize your chances for the sticker upgrade.
As for switching seats, I think that it is a YMMV as I have read posts from people who have done this no problem and thsoe have been red the riot act.