Appreciate the insight. "You learn something new everyday!"
A LONG time if no one is sitting on them. If they are fertile they don't start developing until the hen (or incubator) warms them up. As for how long? I can't give you a specific number but summer before last one of my White Rocks decided to lay out in the shrubs. I didn't find the nest until there were 13, maybe 15 eggs in it. Thus the oldest was at LEAST 2 weeks +, out in the yard in July.
No rooster so they weren't fertile and she never sat the nest anyway. They all passed the "float test". Put the egg in a container of water (a 1 cup measuring cup is fine). If it sinks, eat it, if it floats, don't eat it.
The bigger problem is if you live somewhere that the temps go below freezing. An egg can be below freezing for a relatively short time, maybe a few hours. I once picked up an egg off the coop floor that was laid overnight when it was well below freezing. The shell was cracked, nothing leaking out meaning it cracked as the egg expanded. Once it warmed up to room temp the crack disappeared, one would have to know it was there to see it. But when cracked open, the white was runny and the yolk chalky. It wouldn't have been dangerous to eat but the texture sure wouldn't be enticing.
