I'm currently running a very similar thing over at Atlassian. I was brought in to run their prototyping, and one of the things I immediately noticed is many of the designers didn't have the tools they needed to make proper prototypes. Rather than just teach them on invision/atomic/principal, I figured it'd be better to just teach them how to do front end dev. We're now holding lessons for a 2 hour block every week in 10 week cycles, and that seems to be the best for people schedule wise. Originally we did all day courses but too many people had conflicts. Course notes are here if anyone is interested: http://prototype.guide - also includes a small electron server to help dynamically compile stylus/pug.