That should take approximately as long as a client<->server ping, right? So shouldn't it be irrelevant for JS/CSS that loads within that time (say, 50Mbps & 15ms ping --> everything below 93KB gzipped?)
I still don't see how HTTP/2 Push is solving any real-world problems [1] besides Google being able to push ads so that it counts as an impression even if the client blocks ads.
[1] I don't count the slightly faster initial page load since I'm getting that junk on every page load via push even if I already have it, so I'm paying with my data allowance. If you want your site to load fast, just fix your goddamn bloat.