Welcome! :)
After JS, you can start PHP (and SQL when you arrive to databases).
But I agree with @feuerstein , you can start thinking about the different levels.
Sometimes you need decryption methods, sometimes you need various tools.
You need to learn programming, but you should understand and use different techniques too.
You need to improve your hacker instincts next to programming, but programming is a good foundation.
About python:
It is a great language and easier than C++.
Feel free to start it any time when you wish a little bit relaxation next to web programming.
You can learn python 3 as a hobby.
I wish you to have fun on the levels. :)