I am also struggling with the hip rotation and I believe this is one of the most important part of the swing motion. My problem is that my brain is not able to process all these technical checks(left knee, right knee, left shoulder, right arm angle, etc.) in the 1 second downswing, I need some kind of a feeling that I can replicate from practice in the real swing. Just started to use the lateral shift as a first step in the downswing and I see some better results ... still my hip turn is slow and I really rotate them only after impact... Working on it so I really appreciate any discussion(or dispute) on this subject ...