Too often, people are... beginning their squat while other forces are still in motion, and the last thing that you want to do when you are trying to squat a heavy weight is deal with forces that you did not expect. So make your walkout methodical. Slow it down, take your time, build a ritual that you do the exact same thing with an empty bar on your back as you do with 900 pounds on your back... DO NOT RUSH IT. Once those plates quiet down, your body quiets down, and you have a brace... THEN it is time to initiate your descent.