Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from New Windsor to Valdosta as you normally would.
Due to multiple factors, expect to potentially pay more when booking in September. For low rates, August can be a great choice for travel to Valdosta. Flights to Valdosta from New Windsor in August are about $397 on average during August, but can be found for as low as $230.