The problem with with this approach is that you're only considering time to first byte, which is part of the equation especially in the case of smaller files like scripts, but in case of larger files like video segments, throughput is more important. If you only wait for 1kB to download, then you essentially measure time to first byte.
Then the instruction to stop the download is not instantaneous, so by the time you realize you have downloaded 1kB on the client side, the server might already have sent the whole video segment on the other side, so this is not the way to go in order to optimize congestion
Then the instruction to stop the download is not instantaneous, so by the time you realize you have downloaded 1kB on the client side, the server might already have sent the whole video segment on the other side, so this is not the way to go in order to optimize congestion