I fill out all paper forms and typed dates as yyyy-MM-dd wherever possible. No one has ever been confused by it. Some have even copied it.

I also give units in metric sometimes and set some of my thermometers to C to help build my intuition for what different C temps feel like.

On the other hand I'm setting up a hobby machine shop at home and trying to use metric or a metric lathe would involve too much swimming upstream so alas - it is all imperial stuff.