I think it was 1980. They also manipulated things very well. Much as Woodford Reserve has done, they took pains to get Maker's minis on airlines, targeting business travelers. That in part is what the WSJ article is about. Then they launched a series of humorous, all-text, small-space ads in ... the Wall Street Journal.
But from that point forward, Maker's proved that American whiskey could be sold on quality and could be sold as a contemporary, urban, upscale product, not a country bumpkin like Jack Daniel's. Now we take super-premium bourbons for granted but Maker's proved it was possible, and it only took them 20 years to do it!
Since then, Maker's Mark has grown every year, often by double-digits. Demand has exceeded supply every year for the past 30 years too.
So Maker's started it. A few years later, Blanton's began. Then Booker's and Knob Creek. Then Evan Williams Single Barrel and Woodford Reserve. Then Russell's Reserve started, and Four Roses re-entered the U.S. market, and Barton launched 1792. I'm sure I'm missing a few: Daniel's comes out with Gentleman Jack and Single Barrel, Beam comes out with Black Label, Old Forester does Birthday Bourbon, BT does the antiques, etc. etc., but it all started with Maker's Mark proving that 'premium bourbon' was not an oxymoron.