Not only would it be considered impolite, they don;t do it. Dinner is served in a manner where it comes in courses as that is how the waiter picks it up. If you did not order that course, you just wait until the others have completed it. The entrees are all served at the same time. If you are concerned about the time, (usually an hour to hour and a half spent at dinner), then request an earlier seating.
Jim