I think it's less that you're violating an "arbitrary date formatting convention" and more that you know the formatting convention everyone uses (4 digits), and decide to use your own arbitrary convention that maybe a hundred people in the world use. In fact, you're putting in extra effort just to use this convention that, by the time it's relevant, the earth probably won't even exist anymore.

Most people will interpret this sort of thing as extremely pretentious and also assume that you're fishing for "compliments" and trying to look cooler than everyone else. Like an inside joke only you know about, so will someone please ask you about it?

This type of behavior is typical in a classroom but becomes a lot less culturally acceptable the older you get.