Will you have a car? If so, you could probably do it. If you're relying on Disney transportation, it might be close.
If the parade is at 4 and you catch it right about the middle of the park, you should be out of there by 4:30 or so. Pop is somewhat close to AK, so say it takes 30 minutes to drive, park, get to your room, you're there by 5 freshening up. (Honestly, it may take longer to get out of the park and to the car, but I doubt it would take a full 30 minutes to get to the room.) You'd want to leave the hotel by 6 to give yourself time to park and check in the recommended 10-15 minutes early. Plenty of time.
If you won't have a car, you could also use cabs to get around. The trick with buses is you can't go from resort to resort. Another alternative would be to take the bus from AK to Pop (though you may have to wait as a lot of people exit after the parade) and then cab it from Pop to Poly.