This is my favorite event.
Best advice I have:
Get there at 5pm
Get a spot for the first parade at least an hour before it starts, maybe longer
immediately get into Hallowishes mode as soon as the parade ends
after Hallowishes, do the candy trails while the second parade is going on
If you have a second adult, have them hold the parade spot while you trick or treat. After the second parade, the place empties and you have a solid hour or more to go on attractions with no lines.