Generally, you can do this. If you see your steward, just let them know all you are doing is dropping off in the closet. Sometimes, it has been reported that deck doors are closed in the lobbies of each deck. But I think that is rare as B2B guests will have access to their cabins. Best to drop and take off if cabins are not available. If you do see your steward, they might mention when they think will be done (they will see you are an early boarder versus some of their other cabins).