I know for a fact that Heba Haba AL and the crowd at the New York Lounge in Chicago were doing the 10 count as far back as 1972, when I first started frequenting that joint.
I later worked there as a backup magician, never pulling drinks.
Skeets Mallun used to do it during his rendition of the Benson Bowl routine and Heba used in both the Benson routine and in his standard sponge routine.
The book Garcia did on sponges came out in the late 70's or early 80's IIRC and he describes it in there. However, a caveat on that book. For an encyclopedia, it does NOT cover color changes at all! Nor much on lapping or holdouts for the sponges.
Just some more background.
Lee Darrow, C.Ht. http://www.leedarrow.com