I wouldn't leave a F/T mouse in there more than a couple hours, though some will suggest overnight. Your call on that. As for why he won't eat, could be stress from the move, could be because it's Tuesday. He sounds otherwise healthy, so while this is stressful for you as a new owner, it's just another day for your snake.
If I were you, I'd let him settle for 7 to 10 days, then try again.
If he's been eating two mice a week, I hardly think he's over weight. I'd love to see a pic of him.