Catcher assumes their stance.
The coach tells the catcher what pitch is thrown and where. The coach will give the catcher a few seconds to get ready. When the coach claps their hands, the catcher will assume the blocking position and hold. The coach or other players will check their form to make sure the catcher is in a good position. The drill can be varied by giving the catcher less time between pitch and location and the clap, or the catcher will go on verbal commands only.