Will the ducks be fine in the incubator if I raise the humidity early?

If no one here knows, you might try the incubating and hatching eggs section

 

Ducks (except Muscovies) typically hatch at 28 days.

I'm just now incubating my first duck eggs, too. There's a thread here in the duck section called "Thread formally known as Hatch Day is today" or something like that. Pretty much everyone on there is hatching waterfowl and they can answer your questions.

Also, if you click on the sticky section at the top of the duck or goose section, there is a great incubating and hatching guide written by Pete55.

 

Hey, feel welcome to join us in the Hatch Day thread. You know the one that's a million pages long?

I did the same thing you did. My chicks hatched out Saturday and the ducks just went to lockdown. I candled and it looks like there are several beaks in air cells already!

I don't know how it will effect the overall hatch. This is my first hatch ever and I really made it extra work by setting the chicken and duck eggs at the same time. You should have seen me try to figure out how to remove some of the rails from my turner so I could lay my chicken eggs down at lockdown.

Four out of five chicks hatched successfully. I'm hoping for a good result from the ducks, but it seems like ducks have a harder time hatching than chickens.

I'm hatching runners too!

 

With chickens- you dont need to raise the humidity as high as with ducks- so it shouldnt be too much of an issue. But you should check the size of the aircells once the chickens are done hatching- just to make sure they arent too small. Turning the eggs will be a greater issue for you though. It really is still very important to turn the ducks. Do you have an auto turner?? Some people will put the hatching eggs into a container so they can still have the turning mechanism on for eggs not ready to hatch yet.