This is day 15 for me and I am still nervous.   My broody takes a break every morning and sometimes I set the kitchen timer in case I should have to remind her to go back to the nest.   Meanwhile, while she is up, I feel the eggs and wonder why some are warmer than others.  Then I wonder if she's letting some get cold on purpose because she knows they have quit.  Then I step back and say, I guess Mama knows best.  If day 25 comes and all I have are a bunch of duds, maybe I'll just try again.   Best of luck to you!