[bcbrown]

Pick a small subdomain of your work, and use it exclusively there. Perhaps that's editing config files, or editing when sshed into a remote machine. Maybe for a language you only use in one-off scripts. Something you do at least weekly, but not more than an hour a day. That way you can get regular practice, without a huge productivity drop from going all-in.

Another suggestion: Start vanilla, and slowly add in new commands/customizations slowly. For vim, for the first day, just stay in Insert mode, and move around with the arrow keys. The rest of the week, just add in Command mode, and use hjkl to move around. Next week, add in something else.