CRT instructions I have seen are now outdated. Those were for calling for ADRs. The slots open an hour earlier for the online system making the Disney Dining number a distant second for getting a good, early ADR time.
The general ideas behind the previous instructions still stand:
1) Familiarize yourself with the system prior to your first day you can make ADRs.
2) Double check the date when you can make ADRs
3) Get up a little early and log into the system. As the time approaches (6:00 AM Orlando time), hit the refresh button frequently to get the first opportunity to book.
4) If staying onsite, booking later in the trip may help
5) Have your CC ready. You will need it.
