Nifty,I may sound dumb.But do u mean that if the egg is fertile at laying and you keep it out for how many days? Is this when the incubation starts.I have hatched so many eggs and still have ?`s. I have 3 LG,and this is the 1st time I have used them instead of the Hova Bator 1588.The reason my thermostat started going nuts.It would not stay at 99.5.It went up to like 105-106.And should I fill all the troughs with water and just wait.Yesterday was day 18 sorry jumped the gun,lol.But I am now talking about my LGS with Circulated Air.Any Help would be so wonderful,Thanks BackSwampGirl Sandra