It depends on what kind of ducks you are incubating. Muscovies take 35 days to hatch. Calls take about 23-26 days. Other breeds take 28 days. All waterfowl should have at least 65% humidity during incubation, and 85% during hatch (last 3 days). You also need to lower the temps 1 degree the last 3 days.
Turkeys are about the same as chicken eggs for temp and humidity, though I have yet to hatch turkey eggs. Chickens should have about 45-55% humidity days 1-18, and 65% for the hatch.
All birds take the same temperatures for hatching, but some need lower temps in the end.