On the two days I have in MK, I have PS's for dinner at two of the monorail resorts. They are both for 7PM. Are these early enough seatings to get back in MK for 9PM Spectro Parade?
Just to be safe I'd make your ps's for 6:00. It generally took us 1 &1/2 hours for sit down dinners. Besides that it will probably be pretty crowded since they don't do spectro that often and you might have to fight the crowds.
I would change the PS to 5 or 6. This way if something goes wrong at the restaurant,(long wait for a table or your meal) you can still make it to the parade in time.
I think you need to grab a spot for the parade by about 8:15, 8:30.
DS and I tend got our parade watching spots an hour in advance.