Hello Club,  I hatched last year with broody hens.  Lots of fun and joy, but I am so impatient.  
This year our town feed store has a large incubator, and I am taking charge of it.  So far, they are hatching as planned.  I may just build up my Serama flock again.  I lost them all last year when the snow came down.
Anyways, we had a temp spike with the incubator the first hatch.  The eggs hatched on day 23.  There are threads about that.  Did you have a temp. spike?  That is when the cold weather brings up the temp. in the incubator.
Have a great hatch!!!