That's something I do fairly frequently. There's generally 45 minutes between the end of MSEP from Town Square and the start of Wishes.
There's not usually a rush after the parade to leave the park, so you can pretty easily catch the express monorail over to the TTC. Even if you have to wait for the next monorail, they come every 3-4 minutes. The TTC location is the emptiest, and the quickest route to parking if that is your goal.
For the Poly, either take the resort monorail, or the resort launch. The boat can be more iffy to time than the monorail. If you feel the line might be too long for both, take the express to the TTC and walk to the Poly. Getting there after 9:30, you probably won't be able to grab a chair on the beach, but you can still watch from there.