We have the waterpark option and are going to a waterpark our first 2 days not going to a regular park until day 4, so my question is do I count my 30 days from the first waterpark day or regular park day??
You have to book each day individually if you stay offsite. So 30 days before your first park day, you can book fast passes for it. Next day, you can book passes for the next day of your trip, and so on.