Obviously I physically do it with a slight bump of the left hip and then a turn of the lower body like any athletic movement, but what I am THINKING about doing is different almost every day. Some days I am thinking about tracing the planeline with my right forarm, some days I am thinking about aiming the hands at the ball, some days I am thinking about driving the right shoulder down, and lately I have been thinking about nothing at all except trying to keep my head still and my left wrist flat. Initiating the downswing is something that I have never been able to get a solid feel for doing and I change what I am trying to do constantly. Visually, it never changes much regardless of my attempts or feels.