This may be a dumb question, but I will ask anyway because I can't really get a straight answer off of google. We aren't planning on going until April 2017. What exactly is the expiration date on tickets? If I were to buy tickets now (or, a couple at a time as money presents itself) would they end up expiring before we could use them? Or is the expiration date dependent upon the FIRST day that you actually use the tickets? Do any of my Universal guru's know??