If I’m looking to become proficient at front-end, should i take Responsive Web Design course before taking courses 2 and 3 ( JS and front-end libraries)?
This is just an opinion: If you are able to build 2 or 3 websites from the projects, at the end of the course, you can move on.
I myself never did any of the courses in the right order, but I come back to them and play with the code very frequently. Just make good use of the courses, in a way that works for you, and that’s it.
front end libraries and frameworks need you to be familiar with those before starting
if you are familiar, go ahead, if never done them, need to start from the top
agreed. Responsive Web Design is about concepts, if you have not the principles, will be difficult to understand the course. maybe will understand a lot of things only after a couple years.