Hello, Mary,
I have all sons who are in their teens, and they still enjoy eating at Cinderella's Royal Table. The experience is so regal and elegant; truly worth the extra effort in making the reservations.
The best bet to making a reservation is to mark your calendar when you are 180 days away (Do a Google search for
Priority Seating Calculator to find the exact date). If you are a Disney resort guest, you can make 10 days worth of reservations when you are 180 days away from your arrival date, which will you give you more opportunities to find availability.
Then, you can access
Disney Dining Online Reservations at 6:00 am EST on that day. You'll need your Disney Confirmation Number (if staying at a Disney resort) and a credit card nearby. I'd encourage you to have your ideal time and date and begin with that. If your first choice isn't available, then move onto a second one and so on and so on.
If you'd prefer the assistance of speaking with someone, you can call Disney Dining at 407-WDW-DINE at 7:00 am EST on that same day.
My fingers are crossed for you!