I think if you leave by 10 you should enough time to take the monorail to the Poly. I wouldnt wait too much after as it can take maybe 20min or more to get to the Poly and by the time you leave the park , wait for the monorail, check in etc it takes a while. I would go for 2 hours because on an emh you may be able to get quit a bit in before crowds. After breakfast you could then take a break or take the monorail to Epcot or head back to Mk.