If the park opens at 9:00, you won't be let in early at all since actual opening is around 8:45. You'll be let in with the crowds. So, no, you won't have time to ride 7DMT BEFORE your ADR, and the line will be very long when you finish eating.
If 7DMT is your goal, you need to cancel that ADR and/or keep trying for an earlier one. Even if 7DMT isn't the goal, you'll be eating during that golden first hour of lower crowd touring. By the time you are done with breakfast, lines will be long just about everywhere.