Question: How long is long?
Answer: Long enough to pull every single hair out of your head one at a time and still they haven't hatched!
My runner ducks take 36-48 hours from pip to hatch. The "pip" is the first little hole in the shell--looks like a dent pushed outward. I always get excited when they start pipping, but after that they usually don't do ANYTHING for about 24 hours. Then they'll expand the pip a bit, and then rest for several hours more. Then they expand it again and start unzipping the lid. The zipping takes another one to two hours. Then finally they start pushing the lid off, and even that can take 20 or 30 minutes.
So sit tight. The worst thing you can possibly do is get impatient and try to help them before they're ready (you can cause them to bleed to death if the membrane ruptures with blood vessels still active in it, plus opening the incubator can cause a sudden drop in humidity that can leach moisture out of the membranes and cause unhatched ducklings to get stuck in the shell). The BEST thing you can do is to leave the house, lol.
I agree about humidity. I don't actually measure mine any more--I've found that if moisture is condensing on the inside of the windows, then it's humid enough, and it's not possible to make it TOO humid. When I was measuring, it tended to be between 75-90% humidity during the hatch. I run very LOW humidity during the first part of the hatch.
One thing I would recommend to you as a first-time hatcher, is to measure the air cells right before lockdown. Just take each one out, candle it, and draw a pencil line around the top of the egg where the air cell is (the bright white section, hopefully at the large end of the egg). This does several things for you: It tells you where to expect pips (almost always inside the air cell, and usually on the side that is deepest--so you know which way to turn the eggs so you can easily see pips when they occur), notifies you if something is amiss (like a pip at the wrong end), and gives you a reference point for later. Eggs that make it to lockdown but then don't hatch often have an issue with the air cell size, and if you know what your air cells look like this time, you can make adjustments to your next incubation to improve your hatch rate next time.
For reference, the air cells at this point should take up at least a fourth of the total volume of the egg. One third is even better. Much less and your ducks will have trouble hatching (another thing about doing it right now, is that if the air cells are too small, you can help them develop a little more quickly by lowering your humidity and spritzing them with warm water twice a day until lockdown--then raise the humidity back up again & stop spritzing).
The MOST important thing to do, though, is to HAVE FUN and POST PICTURES.
