"Was it while the killing was ongoing? Or was it only after the last Jew was killed by Hitler that what he was doing could be described as genocidal?"

It WAS genocide when he killed the first Jew (and others by the way) after planning a systematic extermination. During the time he was exterminating Jews, it WAS genocide. And when the killing of Jews was ended, it Was Still genocide. Even if there might have been a day, perhaps Weinachten, during that period when not a single person was exterminated, it was still genocide. Nice try using the word 'genocidal' to try to obfuscate your point....but no cigar.

"Slow learners": is that some sort of ad hominum attack that you criticize others for?

And I still don't know what you mean by an 'accomplished genocide'. I'm beginning to think you don't either.