You can wait until you get to the restaurant and they will credit your credit card and use your dining credits.
You can also call to have it done, but... there have been infrequent reports that the phone CM cancelled the reservation in order to rebook with the
DDP, and the reservation was lost in that short period of time.
I have been in this situation before and I have waited until we got there to take care of it, just to be on the safe side.