A month into Knights of the Frozen Throne, so circa September 2017. I'd previously tried it for an hour or two when it first launched but it didn't draw me.
I was invited to the beta back then and enjoyed it, but am only playing intermittently for a few seasons when I feel like it. Always keeping up with the constant, expensive expansion cycle is too much for me. This way I can dust my obsolete cards every now and then and craft a current deck or two without spending money.
I played in the beta and didn't enjoy the game at all. Completely forgot about it until Gadgetzan. I heard about the old gods stuff that happened in between and returned... Then never left