Up to you, but currently your polling endpoint just has a boolean, which is likely super easy to cook on the server side but also leads the user left wondering "uh, is this thing on?" in ways that any kind of percentage might not. IOW, how long, exactly, should any sane person wait for it to be {"status":true}?
Also, you have your ELB misconfigured because trying to upload a binary that is takes more than 30 seconds to upload causes the actual POST to puke. I'm sure that's great for hello-world.exe but is absolutely hilarious for any real binary
I like to give it bomb executables (reverse engineering challenges) to test it.