I had a miserable hatch first time around using thermometer & hygrometer provided with my foam incubator. 3 of 6 fertile eggs died early on, 2 about 1/2 way thru and one developed fully but never pipped. This time I bought a hygrometer designed for hatching and found my settings were way off for both temp & humidity. I started the next batch of 8 eggs under a broody hen but the eggs I received did not look like the breed I had paid for should so I ordered from a different seller and rotated the lighter eggs to the incubator about a week later and put the darker eggs under the broody hen. I will let her hatch & raise them. The eggs now in the incubator went under the hen on 3/18/13 and were moved to the incubator on 3/25/18. They are on lockdown now and due to hatch on 4/8/13. I have been tweaking the temp humidity after rasiing it from 30%. This evening I went in to check where it was at and noticed 1 egg has already pipped.
e I am thrilled, of course because it means I willl likely actually get live chicks this time, but isn't it too early? It's only Day 19. Does anyone know why this would happen? Will this be bad for the chicks? Should I be concerned? 

