It’s totally false that you have to do the upgrade before you use up the current ticket. Totally false. Even if you use up ALL of the entitlements on the ticket, you can still upgrade it, as long as you do so within 14 days of the first use of the ticket.
It’s a statement that I see talked about all of the time, but it’s just not accurate.
One other piece of advice I can give you is to make sure you use your ticket at least once (for admission to a theme park, water park, etc.) before doing the upgrade. it’s complicated, but the bottom line is that if you buy a ticket at any discount from the current gate price, and then you go to upgrade that UNUSED ticket, you’ll be charged not only the amount of the upgrade but ALSO the price difference between what you paid for the ticket and the current gate price.
Like I said, I know it’s complicated, and I know it doesn’t seem to make much sense, but it’s 100% accurate.