I had 4 eggs left in my Mini Brinsea Advance.. 3 of them all hatched within hours of each other .. they started pipping the eggs on day 20 and all hatched on day 21 within a few hour time span. Now i have this one lone egg.. no broken shell.. nothing.. I candled the eggs throughout.. This is a dark maran egg so they are hard to see inside.. How long do I give it? thanks for any help!