The park opens at 8 a.m. during the fall and winter. You can get there at 7:30 and be checked in and set up with your dolphin swim time, ID and park map. But you'll be waiting in the reception building until 8 a.m. when the park is set up for you. At that point you will go down have your ID checked and your family picture taken, if you're traveling with multiple households they'll make a copy per household, so if I went with my sister and her husband we would get two copies. If we went with our parents we'd get three.
Then you'll go down to a semi-centralized area where a team member will give you a brief over view of the park, it's small but confusing so pay attention. They'll then send you to breakfast or to another team member who will then tell you where to go to get your locker. Breakfast is usually the better idea, since if it's 8 a.m. your dolphin swim won't be until at least 9 a.m. and if you wait for breakfast you'll be starving.
After that you'll go to your locker, wetsuit and changing area, there are three of them, and each has a set of lockers, a wetsuit/vest distribution area and a changing room with bathrooms and showers. This is probably the best place to ask about where your dolphin swim will be.
Don't get to your dolphin cabana more than ten minutes early, especially if you have the first swim, chances are the host won't even be ready yet. Five minutes is more than enough.