I totally understand about the multiple and unknown hatch dates! So embarrassing for me when everyone else on here has much closer to clockwork precision figured out! Haha!
If they have pipped into the air cell, that's when they start peeping. I'm gonna guess within 24 hours they will pip externally and then it will get louder. Mine lately have been pipped 24 hrs before they start zipping, and some longer, and only the fact that they seem stronger and louder and active and responsive to clucks and other peeps has enabled me to resist the urge to 'help them' to death! I have learned so much on this forum! Thanks to all the ladies for sharing their experiences, both veteran and newbie, both good and bad. Helps me reduce the number of sad situations I will have!
As to the unknown hatch date, I just found about 14 in the tractor tire sand box/junk pile last night and from candling, some have some obvious development due to our over-100 degree days like ***bbgranch*** said, so all of them are in a warm outdoor place for today so I can get the current hatch over and put them in the incubator. It won't hurt them to have 1 day of high humidity this early, so I may layer them on the bottom and cover with a non-slip liner and put the other hopefuls on top till I have time to water-test them.
Good luck on the hatching and keep us posted, hopefully with some pics! God bless!