Correct me if I'm wrong since this is my first trip in several years. But the CM we talked to when booking our ressie told us that when we checked into the hotel they would give us all of our tickets including our meal dining card. So if I understood correctly you could start using your dining plan the night you arrive, just stop by the hotel first.
We are actually arriving before check-in time. The CM told us we could still come by hotel first,drop off luggage and pick up our tickets and meal cards and be on our way the first day we arrived.