Incubator eggs on day 23

[EmilyZ2012]

I've got 4 eggs in a still-air incubator that are now on day 23. I realize that my temperature was slightly low at 99.5-100 degrees during the whole incubation period. I'm not at all worried about the eggs because I very quickly candled one this morning and there was tons of movement. My question is will I still see the beak in the air cell 24-48 hours before hatching? I didn't see it in the one that I candled, making me think that it still has a few more days before hatching. The eggs are from my very own Buff Orpingtons, and I think I've done everything minus the temperature, correctly.

 

[Fuentes Farm]

you know i think they all have a mind of there own and come when they wont lol last week i had 4 in a still air incubator and i did they same thing low temp. so they started hatching late in the day on day 22. 2 hatched fine one pipped but died i should of helped but im new to this and lessened learned and one was alive but just didnt hatch. i think what happens is there weaker from the low temp so keep a eye on them and theres lots of threads on here with great info.