We always had contribution boxes at our group study going back as far as I can remember, 1950's.
However, when the new arrangement came in for World Wide Work and Societies Kingdom Hall Fund etc there was a directive that although the contribution boxes continued at the groups, this money was for the the local kingdom hall account. There were never any contributions taken at the group for the WTS.
Of course all this stopped a couple of years ago when the Tuesday group study arrangement in homes was stopped.
George