Shortest I've had was 53 days. On the other side though we have one clutch that still has babies coming out on day 66 right now. I know the temps were good as other clutches in the same incubator were hatching in crawling out by day 56.

While Jeremy's math is good we also have an issue with more variables, such as time out of incubator to check on the eggs, temp of water added during incubation, and the list goes on. Actually I was looking into a little due to the recent clutch and found some references putting some varience of incubation time up to a genetic variable.