mine will go half broody on second day the eggs haven't been gathered on the older ones, but I had one that just started laying at 4 months old and was acting all broody with the first egg she laid, each chicken it can vary what will trigger broody
Biggest worry that long is eggs not being gathered and attracting predators that are after the eggs seeing as nobody is there like usual, I would think. Also not so much of a worry is one of the hens goes broody