If you are parked and getting out of your car 1 hour prior to your flight, you should be in good shape. The biggest variable coming to BNA is traffic, and since you are coming in the night before, that shouldn't be an issue. I prefer to park in the LT parking at the airport. With roller luggage, I always walk from the lot thru the garage to the terminal, a short 5-10 minute walk that is often faster than waiting on the bus.

George Dickel