1. Be there as early as 90 minutes before the "regular hours" park opening time, if you like.
You don't HAVE to be there that early, but that's approximately when the ticket booths will open.
2. Well before that.
(Arriving at the gates 40-50 minutes before the scheduled opening time should be just fine.)
Robo - you're the best - thank you! I had to ask as I just read that one of the parks only opened a few minutes prior - I was nervous we would arrive toooo early.