I have flown out in the earliest flights (around 6am) and the airline employees get there around 4:30am- 5:00am and also TSA employees. They would let you in around that time. Is a small airport so if you want to arrived earlier you can,but if it's to early you will have to wait until the employees arrive. (They have seating area inside the airport)
I've been there before 4 a.m. otherwise, it's an airport so probably 24/7.
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