I'm pretty certain on the start date. I waited until I saw that she had stopped laying eggs and was sitting full time on the clutch. I'm constantly out visiting my ducks, so it was pretty easy to figure the day she started setting. Today is day 40.When my muscovy brooded eggs, I could smell the bad egg toward the end.
I wonder if the actual brooding started later than what you have figured? They start laying the eggs, but the setting starts later on once they have a full clutch. Keep us updated!
But look! Shortly after I posted last, this little one surprised us. I hadn't seen my mama off the nest since yesterday, but about 1pm I heard some peeping under her and by 2pm this little guy appeared. She's got another egg under her that you can see is in progress. Better late than never, I'm so happy to see this little one!