You have never seen anything proven, because part of his deal was to keep the proof hidden from the public. But the allegations were that he was betting in 1984, and he was a player/manager through the 1986 season. Now, you can choose to believe that he didn't start betting until 1987 if you wish. No one in the state of Ohio believes that, but you can believe whatever you wish.Wait. I have never seen that definitively proven.
In Ohio it is pretty well accepted that he was betting on baseball throughout his career, and that it really ramped up when he returned to the Reds in 1984.