Is your broody still sitting on the eggs? Depending on how cold they get they can survive temperature fluctuations for short periods of time. The further along the embryo is in development, the more tolerant of temperature change it will be.
Depending on how bright the candler is and what color egg you're candling you can usually see development by day 3 in a white eggs, but it can be difficult to see anything in a dark brown egg until day 5-7 sometimes even day 10.
This is my favorite candling example of a white egg when I was hatching Polish. I have lot of candling images if you know what day they're on and what color shell you have I can try to find one that should be similar to what you should see.
