Yes you can usually call days before even the day before. If you are going during a busy time like Spring Break call 60-30 days out if you want a certain time. If super busy like Christmas week 60 days out.
Also
DLR doesn't have ADRs, it only has reservations for dining. Reservation only require a name, no CC charge or number.
Usually the only ones I'd say are musts at 60 days is holiday meals: thanksgiving dinner, Christmas, Christmas eve, and new years eve. But if you know the when and where you want to eat I see no reason to wait. I've made reservations a few days before even Christmas week with plenty of availability, but the "big" holiday meals fill quickly.