True, it was like half a day of extensive coding for the basics, a bit of cursing, then about two weeks of settling in and then a few hours over a couple of months, when I did heavy extension and configuration.

Bonus: my window manager has similar keybindings these days

Yes, do it this way. When I learned vim, I just went to work and decided to use it one day. The only thing I did was get on Stack Overflow and look up how to turn off the arrow keys, so I would have to use hjkl.

As you said, by the end of the workday I was very comfortable with basic vim use.

Print a sheet of basic commands, tape it to your monitor and off to the races.

While a weekend is quiet an exaggeration (2 weeks of 1h/day practice is more likely), the point of amortization still hold.