How long does it take to learn multiple programming languages?

Honestly, if you're just reading large textbooks without applying what you learn, you might feel lost and not get much done in three months. It really depends on your goals and how you usually pick up new languages—transitioning from one to the other is usually about syntax if you already know the basics of programming.

It looks like you might be spreading yourself a bit thin without a clear reason to learn multiple languages. If you're comfortable with JavaScript, picking up R and PHP shouldn't be too tough since they share similar concepts. Just a heads up, though—React isn't a programming language but a front-end framework, which is super useful for improving your site.

Without a specific goal, it's hard to say how far you'll get in three months. If you're just aiming to have these languages on your resume, make sure you can show practical projects you've done with them. That's often what interviewers care about the most.

I'd suggest figuring out what you want to achieve by learning these languages first. Jumping from JavaScript to a lower-level language like C++ can be a big leap, so be ready for some new concepts. Creating a roadmap for your learning could help, and remember to give yourself time to absorb the material instead of rushing through! How you apply what you're learning matters just as much, if not more.