2013:
September: 10, 13, 17, 20, 24, 27 & 29, 2013
October: 3, 4, 6, 10, 11, 14, 17, 18, 20, 22, 24, 25, 27, 29 & 31, 2013
November: 1, 2013
Hallowishes is historically at 9:30
Parades are 8:15 and 10:30
The party is 7-midnight, but you can enter MK as early as 4pm with just your party ticket (I know you said you have your tickets already, but just fyi).
I have been to
MNSSHP 4 or the past 6 years. I highly recommend it and it is definitely worth it. The parade and fireworks are great and the entire atmosphere of the party changes to Halloween at 7pm, although it is Not So Scary.
There are party-only character meets, dance parties, Villains stage show, special photopass shots and trick or treating. There is so much to do the ride lines are very short.