Hi Dawnrose,
It will be tight...depending on wherre you watch it from, the parade may not be finished at your spot till 4:30. Then you have to buck the crowds, many of whom will be leaving with you! Then you need to get back to the bus stop or your car, and if you're using WDW transportation maybe you won't get on the first AKL bus.
I'll defer to someone more familiar with MJJP, and you may indeed make it back in time, but I'm thinking it will be close!
Good luck!
Bob