Presumably your backend at this point is not ultra optimized. If you send a link header and using http/2 the browser will download the js file while your backend is doing its thing. I'm doubtful that moving js to the edge would help that much in such a situation unless the client is on the literal other side of the world.
There of course comes a point where it does matter, i just think the cross over point is way later than people expect.
Absolutely:
https://wondernetwork.com/pings/
Stockholm <-> Tokyo is at least 400ms here, anytime you have multi-national sites having a CDN is important. For your local city, not so much (and of course you won't even see it locally).
Images: 1MB
Javascript: 35MB
Fonts: 200KB
Someone who is good at the internet please help me budget this. My bounce rate is dying.