Any thoughts on staggered hatch?
Yeah, don’t do it. Start all eggs under a broody or in an incubator at the same time. Don’t leave eggs other hens have laid under the broody after incubation starts. Then you know the schedule. But instead of always having the “ideal” situation, I sometimes have a situation “I deal” with. You have one of those.
If you have a second incubator, set it up as a hatcher. Put the most-developed eggs in that.
If you don’t have a second incubator, you can just put them in your and continue with the normal humidity regime for the largest number of eggs or the most valuable eggs. This is the safest way for those more valuable eggs. The earlier ones are at a higher risk of shrink-wrapping when they hatch with the lower humidity, but these things don’t come with absolute guarantees. They might hatch OK. Certainly give them all a chance.
I have opened the incubator several times after eggs have pipped to deal with a situation. I did shrink-wrap one doing that, but only one. All the others that had pipped did not shrink-wrap when I opened the incubator. It’s a risk I’m willing to take if I have a real reason to take it, but it’s not something I do lightly.
You can try upping the humidity if you see one rocking, hear it peeping, or see a pip. How much is that going to hurt the other later eggs? Depends on how much moisture they have lost and how high you raise it. There is a range of moisture loss that will work.
Then you have the turning problem. Chicken eggs really don’t need to be turned after about 14 days. Early in the incubation when the body parts are forming, turning helps them form in the right places. Also, if the egg yolk or developing embryo comes in contact with the inside of the egg shell, it can get stuck. But after 14 days, body parts have formed and a membrane is in place that protects the developing embryo from becoming stuck to the inside of the shell. That’s the same membrane that can shrink-wrap a chick if it becomes too dry. It’s traditional to turn until lockdown because it is so convenient to take the turner out and up the humidity at one time, but it really doesn’t matter if the egg is turned from about 14 days all the way through hatch. Maybe knowing when turning is actually required (the first 14 days) can help you manage your staggered hatch.
There can be another problem with a staggered hatch. When a chick hatches, it can crawl all over the unhatched eggs and smear them with gook. They’ll poop too. This gook is a good medium for bacteria to grow. It can infect the unhatched eggs and kill the embryo inside. It can also stink. Again, this will not happen each and every time, but it is a risk. You might craft a basket out of hardware cloth to put over the earlier eggs to keep them off the later eggs. Many people would not bother with this but I’ll just mention it. Like many things just because something can possibly happen doesn’t mean it is guaranteed to happen. I just think it is a good idea to know what the risks are and take reasonable steps if you reasonably can.
I remember only one time an egg has actually gone bad. Many decades ago when I was a kid on a farm, a hen hid a nest on the ground in a brush pile. We didn't find it until the chicks were hatching. She hatched most of them out, but one egg had obviously gone rotten. It did not explode but it was weeping a liquid with a rotten egg smell. That's something you want to avoid but in my experience it does not happen that often.
I have not been in that situation so I cannot tell you what I would do. Sometimes what you know in theory isn’t what you actually do in practice. Not knowing the schedule of the eggs from the broody makes it even harder to guess what to do. Hopefully this will help with your plans. Good luck!
