It doesn't take much digging to find sources older than that, really. ;) For instance, you can check out my own post about it at http://www.clevcode.org/cicada-3301/, originally written mid-January 2012. The oldest comment on the post is from 2012-01-14. There were articles written about this back in 2012 as well btw.

PS. I'm the Joel Eriksson that was interviewed for the article in question.