I candle them (all kinds) every evening. When I see internal pips, then I lock them down. If your incubation temps were running a bit low, that will slow the babies down, and unless you're running a true thermometer, it's hard to tell. I have my Incuvue thermometer adjusted around 3°. It was off by that much. Nearly all of them are considerably off. And of course the temp will vary according to where in the incubator any particular egg is. I move mine around once a day, when I candle them--I imitate the way a school volleyball team rotates its players.
You might enjoy the
May hatch-a-long thread. There are lots of folks on, many very experienced. It's a great place to get any advice you might need as well as share your baby pics and stories.