With that early a departure, I'd personally plan for eating at the airport.
Don't forget about rush hour traffic.
I suggest probably that you go ahead and make the ADR, but be mentally prepared to cancel if you get crunched for time.
Our family tends to like to stay out as late as we can the night before we leave, so a departure that early would be tough for us on it's own...but maybe you are morning people, in which case you'll have plenty of time.