Thanks @trickyearlobe - I now get a glimpse of the start screen. Still to short though. Applied @fba 's configuration, but it seems to make no difference:
Can't see what's wrong with it:
# head 200.conf
args: -boot menu=on,splash-time=20000 -vnc...
Is there a way to increase the time window for pressing ESC?
Between reset, switch to the noVNC console and pressing ESC I'm just too slow. And I don't feel like doing video game exercise just to get the sequence right in so many millisecsonds.