I walked the opposite way, from MGM to Epcot one night. Out of curiosity, I timed my walk-exited MGM at 7:44, entered IG at Epcot at 8:14 (looked at my watch with the security man's flashlight at the entrance. This was before I knew of a little shortcut to save a few steps, too-when you're walking along the Boardwalk, take a left just before the Screen Door, past the Wayland Gallery (I think); go thru the "tunnel" to the Boardwalk pool (there's restrooms and a workout room you'll pass in the "tunnel"), bear left around the pool and out onto the walkway toward MGM.