Yeah, I have read on other sites 23 days, and most people on here say 26 days, so I would just stop turning around day 21ish, just to be sure.
What do you mean by 'my air cells in those are getting small'? What day are they on??
The humidity should be about 70% during incubation, and 85%+ for the hatch, if you can get it that high. A lot of people say they set theirs with chicken eggs with no problems, but I personally wouldn't risk it. I do have some set with chicken eggs right now, but the chicken eggs will be out before the ducks are halfway done.
And I think mine is worse! Right now I have button quail and silkies in the hatcher, due tomorrowish. Then I have some coturnix from a swap due on the 26th, then I have some cochin eggs due the 29th, some more quail eggs due the 30th, then ducks due the 10th, and again the 17th, and your calls are due the 14thish.
And I'll be setting some more ducks