We did this in February and it took AGES!!!!! (Or at least it seemed that way because we wanted to get in the park!) I was going to try to upgrade them in the park, but DH said we should "get it out of the way" so we upgraded them at the turnstiles before you get on the transportation to MK. The lady was pretty confused because when she scanned our tickets "we had not bought them through Disney" so the computer said to charge us $110 for the upgrade. I said: "No way, it says right here the upgrade should be $55." So, she had to call her supervisor and they had to go through some silly hoops, but we did upgrade our tickets (for $55 plus tax) and ran into the park. It did take about 40 minutes to do this... which seemed like way too long for something that should have been routine. The lady was pretty nice about it and gave the kids lots of stickers because of their wait!