The Superhost designation began in 2014. It must have started close to when I did. I found an Airbnb facebook post from Oct 2015 that says “one year after we launched the Superhost program…”
Also, in 2019 I got a thingy/award for being a superhost for 20 straight quarters/5 years/since the program began. I posted about it here
It’s not that important, I’m just a stickler for facts.