I put 6 runner duck eggs under my broody and then 5 chick eggs 7 days later. Supposedly they will all hatch on the 28th. What if I screwed up and some hatch and she leaves the nest early. It would be my fault and I would hate to compromise any of these babies. I have candled, I know we have some of each that are growing. Should I buy an incubator just in case. If she leaves the nest and I don't have one, I will never forgive myself. But I have no intention of incubating eggs otherwise, so it seems excessive.
Do you have an electric skillet or toaster oven? If so follow the link in my signiture line. If not they will be so close to hatching you probably could take a small ice chest with a small light bulb hung in it. You would have to adjust the temps by opening the lid in small incriments. I know it sounds odd but, some of the eggs in my bator right now were started that way while I waited for the skillet to become available and then Mother's Day rolled around and I got an incubator.