Here's when day one of Disney Plus.
The Simpsons season 1 aired in 1990, and those early episodes aren't quite up to the standard the series would eventually become famous for. The animation is crude, the voice actors hadn't quite figured out their characters yet (Homer still sounds like his early inspiration, Walter Matthau), and the stories are hit or miss. But The Simpsons really began to realize the show's vast comedic potential in season 2, which has some memorable high points: the annual "Treehouse of Horror" Halloween specials began and "Two Cars in Every Garage and Three Eyes on Every Fish," when Citizen Kane was a favorite subject for parody). The Simpsons also really began to dig into the emotional lives of the characters and stuck paydirt with episodes like "Lisa's Substitute" (with guest voice Dustin Hoffman)" and "The Way We Was," the heartwarming story of how Homer and Marge met in high school.
However, The Simpsons season 3 and 4 are what most fans consider to be the true beginning of the series' golden era, with many major celebrities guest starring. In the season 3 premiere, "Stark Raving Dad," The Simpsons scored one of their biggest guest voice coups ever when Michael Jackson appeared as a mental patient who thinks he's Michael Jackson. Hit after hit followed: Krusty the Klown's Jewish upbringing was explored in "Like Father, Like Clown," Germans bought the Springfield Nuclear Plant in "Burns Verkaufen der Kraftwerk," Aerosmith performed as Moe the Bartender stole a cocktail invented by Homer in "Flaming Moe," Sting appeared as himself to help rescue Bart when he fell down a well in "Radio Bart," and a batch of Major League Baseball all-stars like Darryl Strawberry, Jose Canseco, and Ken Griffey, Jr. became ringers for Mr. Burns' softball team in "Homer at the Bat."
The Simpsons season 4, meanwhile, may rank as the series' best season overall. Virtually every episode is an all-time classic, especially Luke Perry, who was revealed as Krusty's (worthless) half-brother.
By The Simpsons season 5, the series' golden age was truly in motion: "Cape Feare" is Sideshow Bob's (Kelsey Grammar) best attempt at Bart's life, Homer nearly has an affair with his co-worker Mindy Simmons (Beatles, Ringo Starr and George Harrison, guest-starred on The Simpsons by that point (Paul McCartney would later make it a clean sweep in season 7).
Thanks to the series' original writers - led by the late Sam Simon, including showrunners Al Jean, Mike Reiss, and David Mirkin, John Swartzwelder (who wrote over 59 episodes), George Meyer, Bill Oakley, Josh Weinstein, Jeff Martin, Jon Vitti, Greg Daniels (who would go on to create The Office), and Conan O'Brien - the early-to-mid-1990s era of The Simpsons was when the series really became, in Mr. Burns' parlance, excellent.