You are no more qualified to be a CrossFit coach on the Monday after your cert than you were going in. How do I know this? Simple -- because I was the world's shittiest CrossFit coach for easily two years.
The body is amazingly tough at handling abuse. But do something a hundred times, do it regularly, do it when you are tired, when your shoulders are already sore... something is going to give. Something. Is going. To give.