Truthfully it takes a close eye to recognize a fertilized egg, but it is good to learn and practice as you cook. Check on here for the pictures of fertilized eggs. Chances are you have been eating fertilized eggs most of the time. One does not have to refrigerate them immediately, room temperature does nothing to cause growth.
Eggs are not like mammals in which growth begins immediately upon fertilization. The egg is just dormant until heat of near 100 degrees is applied for 24 hours +. This is an amazing thing, in that it allows birds to lay an egg, wait another day, lay and repeat until the clutch looks right to her. Until that point, she will not sit on the eggs. But when the broody hormone kicks in she will then go and set on the clutch, heat the clutch up to 100 degrees and they will all develop and hatch in the same 24 hours.
Otherwise, some eggs would be hatching and other have days to go...
Welcome to this hobby it is wonderful fun. Hope this helps.
Mrs K