I felt ok with JavaScript when I started learning React, and I'm stepping back a bit to really focus on the fundamentals. I still have a couple of React projects I'm working on, but I'm trying to spend more time reviewing JS. Great post!
Sometimes when people wait to get really good at one thing, they get stuck and cannot move on. I would suggest changing the tone of the phrase to say, learn until you are good enough to get something done.
Learning is a journey, @getify who is nowadays advocating has spent years, and he is still learning.