I went from barely knowing html and CSS to slinging react/redux apps with es6, bundled with webpack, out for paying clients in less than a year.
If you just take your time, carefully go through tutorials and study a couple of open source projects you'll be fine. Especially if you already have years of development experience. You can do it!
This is perhaps why it's not a good idea to learn JavaScript. Since there's a lot of kids down there that learned how to throw something together in the course of a year.
Eh. I started out by learning Javascript and creating a basic CRUD app using the MEAN stack. Year after, I was hired as a contractor at a Fortune 500 company, and then transitioned into full-time at the same company 2 years later. Now I juggle around several different programming languages; I'm honestly glad that I started with Javascript.
If you just take your time, carefully go through tutorials and study a couple of open source projects you'll be fine. Especially if you already have years of development experience. You can do it!