In my work, today's date would be 21K11, to save space over the longer date.
Notably he didn't promise any, but presumably one'd need a separator... Maybe, per his "K" usage of the month, one'd use the alphabet again. 11am would be "K" again... or lowercase just for giggles?
I don't think it reads very well, but I also think one'd get used to it pretty quickly.