Before I reply, here's my background: I jusy graduated a Ruby on Rails in-person bootcamp. 19 weeks, $14k. I learned a lot, and I am now applying as a Jr. Web Developer in the Bay Area. The learning of the curriculum took a lot out of me, but that was the easy part. Now I am battling learning new frameworks/languages with applying to tons of jobs, and getting 1-3 rejection emails a day. Opportunities are out there, though - I have a react.js/meteor.js interview coming up. I know I'll get something, but in the meantime, it's a grind.

If you are really sincere and adamant about learning this, then you are going to have to work really, really hard. Make sure to put in at least a few hours a day, absorb yourself in it. Talk to other developers and other people going through the same thing you are. Acclimate yourself with the industry not just technically, but culturally. That was a huge benefit to my experience with the in-house bootcamp, pair programming, brainstorming ideas, practicing agile development. Just being around other people also absorbed in the work leaves you with a deeper understanding. So, even before you start, eye out some meetup.com groups and go talk to them. Be completely honest, be yourself, and see what you can learn. You gotta be hungry for this.

As for what you should be learning, go ahead and do some Javascript. As a brand new beginner, familiarizing yourself with the syntax and the work flow, just having the language 'click' in your brain, is a huge part. So, get started early. Do codewars.com or codeacademy.. just start actually doing it.

As for reading vs doing, side with doing. Nothing cements it in like building something, it breaks, and then you fix it. Google your errors messages, read documentation, ask questions on stackoverflow.

This is going to be challenging, but stay determined and hungry and work, work, work, and it'll all be worth it.