I have both chicken and duck eggs in my incubator. It's been a week after the due date for both. How much longer should I wait? I marked the area of the air sack with pencil and plan on checking them in a couple days to see if there is any shrinkage. How much longer should I wait. Last time I incubated eggs they were right on the due date. I know it's say a few days after the date but its been a week now.