Well, I certainly learned a lot today about eggs, fertilization and hatching. The last few posts clarified everything. Thanks are lot for your replies!
Probably 2 days. They took my niece to the farm 2 days ago and she returned with an egg. Her parents don't want to do anything with it as they are vegetarians and live in an apartment.
My niece got an egg from her neighbors to have it hatch in her nest toy. Basically it has been sitting at a room temperature. A dumb idea indeed. Can this egg be returned to the chicken farm it was taken from and will that even work?