According to the Wayback Machine, it's lacked a declaration (as opposed to a statement that it's supposed to contain a declaration) at least since December 2014, the earliest version that was archived:
it would be funny if the initial publication of the canary was itself the disclosure. Like this:
[on my hackernews profile:] "I have decided to start publishing a Canary on whether I have ever been hellbanned. The purpose of the Canary is that it can be 'dead', i.e. I can simply fail to state something, and not saying something surely does not put myself at risk of reprisal. Still, the fact of my not saying something can alert you. If this comment ever FAILS to end with a positive statement that I have not ever been hell-banned, then you can take it as an indication that I have been. For now, I'll be keeping this Canary here, but can remove it at any time."
http://web.archive.org/web/20141226030217/https://canary.sil...