Goes back at least slightly before that, as I've had 2038epochalypse.com registered since March 2017, but I can't recall whether I thought I was being clever or whether I heard it somewhere else.

I've had my "2038 consulting" sites since Feb 2011, but someone got epochalypse dot com registered August 2007.

Heh, I've got five domains of a similar name too. Going to reach out to the owners of the website this post is referring to and see if they want them.