2007 was the first year that all teams wore sublimated numbers (The Bulldogs dragged the chain and didn't get rid of stitched numbers until the end of '06). I'd say they became commonplace at the turn of the century. Heat-pressed numbers were never really used.
Bulldogs had sublimated numbers in 2003 then went back to stich on for 04-06 for some reason . Cost cutting measures ?