As long as you haven't entered a Photopass card # on the online account, I don't see why it wouldn't work. How would Disney in any way know from your online Photopass account when your trip is? It's not at all possible! Now, I could see that if you've already added pictures to the account, they might have a way to not let you "pre-order" because obviously your trip has already started! But it just has to work if you don't have any photos on the account!