This February, I got chick crazy. I was just ready to have chicks, but my incubator hatch last time wasn't very good. I didn't want to try again with any kind of expensive or special eggs. Fortunately, Thanksgiving Point Farm Country sells hatching eggs for $.50 each. I got a dozen, 6 leghorn, 6 brown egg layer (later determined to be buff orpingtons), and 1 mystery bantam egg.
What I learned this hatch: I really need a better thermometer. I tried with one of the probe meat thermometers from Wal-mart, but it just wasn't reliable enough. It had this cool feature where it would beep at a certain temperature, so I set it to beep if the incubator got too hot. It would decide it was hot randomly and beep while the other thermometers showed no temperature spike.
Egg turners are awesome. I got an egg turner and had much better results than I had without it.
Results: 10 eggs went into lock down. I had 6 chicks hatch: 2 leghorn, 3 buff orpingtons, and a mystery feather footed bantam. One of the orpingtons hatched on day 18. I was convinced I had run my incubator too hot and killed all the other eggs. Fortunately, on Saturday and Sunday I had more eggs hatch.
How long after the first egg with the other eggs hatch? Well in my case, more than 24 hours.