State parks vary quite a bit for reservation windows. NY for instance has a 9 month window, while FL has an 11 month window, and GA has a 13 month window. We do make reservations well ahead during busy seasons and when we have specific site preferences, and hitting them the instant the window opens gives us the best shot at getting what and where we want. Our Jan-April "southern tour" of GA, FL, and NC state and national parks is fully booked with the exception of a few flexible overnights, and our July 4th week park and site preference is booked in NY, with Labor Day week on the calendar for booking at the end of the month. In between, we'll wing it with booking no more than a few days ahead with a few private sites that need no reservations filling in the gaps.