The latest Study Edition offers a new proof for 1914, get this:
WERE you born after the year 1914? If so, you have lived your entire life during “the last days” of the present system of things.
Because so much time has passed since 1914, we must now be living in the last of “the last days.”
The long dragged out failure of their prophecy to materialize is offered as proof of it being true. Go figure.