Once a chicken goes broody, how long does it take before the eggs begin to develop?

There's a good possibility the eggs arnt duds, because if she wasn't sitting on them that long before they didn't get to form and eggs will keep a few days and still be able to have chickens hatch them. I think I have had a chicken be like this already this year, and she's young so its a good possibility, but I took the eggs from her cause they were getting way to much and crowded in the nesting box.