That's plenty of time.
Most people have this idea they need to spend an entire day in the park to see everything. At SWF, the parking lot opens around 08:30am. Be there at that time, go in, head to the left, and get to the rope. They'll play the national anthem at 9am, then you head towards Kracken and JTA. Eat an early lunch at 11:30am to beat the crowd. For each show, arrive 30 minutes early for the best seats.
I never spend an entire day in the park, my feet get tired. I usually go early, then leave in the afternoon when it gets crowded.