I’m thinking Bill Goldsworthy wore one before him. Teddy Green, before that.
I could be wrong on this… But I think Teddy Green was an injury related helmet wearer, I don’t know about the other guy.
Denis Potvin was the first one I remember wearing it when he came into the league just as a matter, of course.
Of course, it’s been a long time… I’m not sure I trust my memory that well anymore… :-)