Very early on. The real growth of cable aligned with the growth of stations like MTV, CNN, WTBS, etc.
Maybe revisionist but what most people think of as "cable" was broadband cable (maybe DirecTV, launched 1994) with lots of commercial channels. They don't think of having a 12 foot antenna scouring the sky for signals.
There was certainly some earlier cable, e.g. HBO, if you could pickup broadcast, that predated channels like CNN.