This is very interesting.
I attended a sign language class for some weeks sponsored by a local congregation. The language course lasted about 3 months.
It was expected that after the class finished, those in attendance would make the effort to join a deaf congregation.
We learned specialized sign language for theospeak, that is the signs for elder, ministerial servant etc.
I remember seeing a big shot elder who came all the way from Florida to tell us how marvellous this loving provision from Jehovah was.
There was homework given at the end of each class. We started with letters and eventually progressed towards introductions for use on the ministry. Each class was about two hours long, then we would spend about that time in the ministry, but only witnessing to deaf people.
The search for deaf people was vigorous - they would use telephone directories and other sources of information to build a list. If the witnesses saw a "Deaf Child" sign on the street, they would call at every house on that street to locate where the deaf child lived.