I had that happen a couple of years ago. The eggs were on day 19 and already peeping. I felt horrible, because I leave the run open during the day so the hens can come and go as they please.One of my feral games went broody around March 1st. I marked 3 eggs and left her alone. I have 6 nest boxes, stacked 3 and 3. She in bottom middle nest. Yesterday, she moved to the first nest.
Hmmmmmmmmmm.......
Picked her up, she had 6 eggs under her.
NONE MARKED.
I guess I had a visitor, probably a snake. So she started over. Gonna start giving her some supplemental protein, she's been sitting 17 days now, and I know broody is hard on them
I had another hen on day 9, so I moved half her eggs to the girl who had been sitting longer.
One of my 7 month old bantam cochins is broody. I may let her have eggs next week.