I'm not sure whether you mean use your hand as a shutter as in the way people used to (still do) use hats in front of the lens, or as a button-pressing 'timing device'.
The latter is quite o.k. for long times. The barn doors open and close quick enough, relative to exposure times long enough that we can time them ourselves with reasonable accuracy.
So no need for the 'hat'.
A nice condition 201f is on its way to me this week. I hope to have it by the end of this week so I can test it prior to photostock with the Great Wall lens and a short focal length petzval that I am making another body cap mount for.