I don't really remember exactly how long until I felt particularly comfortable with it. Probably on the order of days? I have never really used any other VCS besides vanilla git before, so I didn't really have any mental model of how different VCSs could be different. The whole working revision vs working branch + staging area was the biggest hurdle for me to overcome, and then it was off to the races.

And yes, I use jj locally with remote git repos.