What's the earliest/latest you've had a chick hatch?

[BuckeyeFam]

I know it says 21 days but does that vary?

 

[LilRalphieRoosmama]

Oh yes - especially with the cold. Don't give up til day 25!!!

And

!!!!

 

[Teresaann24]

I had egg hatch at day 26

 

[Boggy Bottom Bantams]

yep, I 've had the go from day 18- 25.
1/2 degree off on temp, usually results in 1 day hatch difference.
too hot, hatch too early and vice versa with the too cool.
Aubrey

 

[Mahonri]

I'm figuring with 99.5 in my forced air 1588 that most will hatch slightly after day 21. Guess we'll wait and see.

I did turn up the thermostat in the house to keep our home at a more even level.

We are used to having it cool at night and I had been keeping the bathroom window open, but our bathroom is on the other side of the wall from the hovabator in the family room and I noticed the first night that the temp had dropped to 99.3 so I stopped that and we seem to be doing fine now.

I also put the little thermometer they give you on top of my leghorn eggs on the right side of the bator and I'm guessing it's right around 99.5 as its as close to being 100 with out being right on as it can be.

 

[Boggy Bottom Bantams]

I have use the same ones numerous times.
You are right on with it, just watch a FULL cylce on the thremostate, from the time the light comes on, til it goes off, note the highest temp at the end and the lowest in the begining, now adjust til the average is at 99.5 and that's what your eggs internal temp will be as the shell insulates them some what and doesnt allow them to cool /fluctuate as the cycle runs on the thermostate.
You are also correct in avoiding any major temp swings in the room temp.
A neighbor of mine kept wondering why he was cooking all his eggs, yet I hatched everyone he gave me.
Well he have his blame incubator outside in the middle of SOUTH GEORGIA SUMMER, in an old cow barn, well it was 75 -80 in there at night and 100= dureing the day, also it was directly in front of a sunlit window which is another no no...so he was cooking them dureing the day why he was at work!
But sounds like you have that figured out already!
Aubrey