Leave them in when they hatch, because only a 2 second drop in humidity can shrink wrap the other ducks. They will roll the eggs around, but at the same time their peeping encourages the others to come out.
You will see dark blotches developing. That happens when they turn in the egg and their tiny toe nails scratch the membrane. Just let nature take its place. Do not touch for temp or liveliness.
It is best not to intervene. They should hatch within 48 hours after external pip, but sometimes they need longer. I intervened with my last hatch. Two zipped and hatched fine, but the rest was not able to zip. They basically had one large hole each with their heads sticking out and were not going around in a circular motion. I've waited as long as possible, so it was the last resort. I don't like to do any of it at all. So don't you even think about it, unless you know it is necessary. Just post pictures when in question and we will advise you. Note the pipping times on a piece of paper for each egg without opening the hatcher. Doesn't have to be 100% exact. It may help down the road knowing these times.
Do not mix on the electrolytes yet. Do it when you are ready to move them to the brooder. I mix on 1/2 gallon and keep it in the fridge. I take a little bit and warm it in the microwave and mix it up with my finger in it. That way I know it is not too warm or hot. Do not store at room temperature, because that is perfect for germs to grow in it.
100 watt light bulb from 24" above should produce about 95 degrees on the brooder's floor. You have to put a thermometer in and play with it until right. Have various wattages on hand. Remember those bulbs will disappear off the market, so you should think about stocking up for future use.
