No, you will not be finished in time to get there before the RD crowds. Even if Castle Couture is open there is no way you can get in both before 9:00
I would do the appointment, go to A&E and get through that and then get photos done
We did A&E during EMH last week. There was zero wait for A&E for the entire EMH time. As in, we finished with the sisters and no one else had come in the room, there was no one else in line. There was however, a line for Rapunzel and Cinderella
The waits for them are never horribly excessive any more.
Also be aware of when you are going. Eventually, at some point this year, they will leave MK and move to Epcot. Just no idea when that will be. late Spring/Summer most likely.