I helped introduce React at UXPin, and that was in Q4 2015. By that point it had already been broadly hyped for at least a year.

The parent comment is broadly correct though. AirBnB couldn't have been a React website in 2012 if React's initial release was May 29th, 2013.

0.14.x was when I adopted React. And yeah, I think it was getting quite popular already. That was released in 29/10/2015, so that matches what you said.