Not parent, but for me it was a couple hours of reading (jj docs and steve's tutorial), another couple hours playing around with a test repo, then a couple weeks using it in place of git on actual projects where I was a bit slower. After that it's been all net positive.

Been using it on top of git, collaborating with people via Github repos for ~11 mos now. I'm more efficient than I was in git, and it's a smoother experience. Every once and a while I'll hit something that I have to dig into, but the Discord is great for help. I don't ever want to go back to git.

And yes, jj on top of git in colocated repos (https://jj-vcs.github.io/jj/v0.27.0/git-compatibility/#co-lo...).

If you set explicit bookmark/branch names when pushing to git remotes, no one can tell you use jj.

(not your parent)

> How long did it take you to become proficient?

As with anything, it varies: I've heard some folks say "a few hours" and I've had friends who have bounced off two or three times before it clicks.

Personally, I did some reading about it, didn't really stick. One Saturday morning I woke up early and decided to give it a real try, and I was mostly good by the end of the day, swore of git entirely a week later.

> I assume the organization uses git and you use jujitsu locally, as a layer on top?

This is basically 100% of usage outside of Google, yeah. The git backend is the only open source one I'm aware of. Eventually that will change...

It's really not that long. Once you figure out that

1. jj operates on revisions. Changes to revisions are tracked automatically whenever you run jj CLI

2. revisions are mutable and created before starting working on a change (unlike immutable commits, created after you are done)

3. you are not working on a "working directory" that has to be "commited", you are just editing the latest revision

everything just clicks and feels very natural and gets out of the way. Want to create a new revision, whether it's merge, a new branch, or even insert a revision between some other revisions? That's jj new. Want to move/reorder revisions? That's jj rebase. Want to squash or split revisions? That's jj squash and jj split respectively. A much more user-friendly conflict resolution workflow is a really nice bonus (although, given that jj does rebasing automatically, it's more of a requirement)

One notably different workflow difference, is absence of branches in the git sense and getting used to mainly referring individual revisions, but after understanding things above, such workflow makes perfect sense.

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.