The start of the forward swing needs to be just as smooth as the beginning of the backswing. The swing never totally stops at the top of the backswing but one of the most common mistakes of all golfers is to rush the transition. Starting the backswing unusually slow is not the answer as the tendency then is to try to catch up on the forward swing.
The best way to accomplish a smooth, overall swing is to picture the tempo of the entire swing at the address as opposed to trying to picture a backswing and a forward swing. This will help you immensely towards a smooth transition.