I agree with the previous poster. They say to allow at least an hour for transportation. In your case you would have to leave your new resort at 6:30am, catch a bus to MK, then either walk over to the CR or use the monorail. I don't think you can get checked into your new resort and get out to the bus stop that early (which you MUST do to get your dining credits).
Last spring I decided to check out of my resort on my last day, thnking I could easily get my boarding pass from the Magic Express desk and still make my 8:30am ADR at Crystal Palace. When I got down there very early that morning, I was shocked at the really long line already there. In your case there will be other people trying to do the exact same thing you are.