For years I've written dates using the One True Date Format,
YYYY-MM-DD, but that may be about to change.
I'm thinking of changing it to
I tend to prefix everything with a date and the dotted notation results in a narrower date (when using proportional fonts) and makes it easiest to scan. “2019.01.09” looks like a single text object, while “2019-01-09” looks like three things, hyphenated. It's hard to explain, but given its space-saving and list-scanning properties, I'm going to try the dotted notation for a while.