That egg doesn't look like its dipped yet are we sure about the days. Ducks usually will collect there eggs even bury them and when they are ready which is usually one week that's when they sit full time. So if day one is counted from the first egg laid I would probably add more days depending on how many eggs are there. Also first time mommies aren't the best and if she's a first timer then I would consider bring them in and finishing the job if it seems like she's not sitting any more. But if all the eggs look like that picture then they aren't ready. I would guess and say you have about another week yet.

