Emergency incubation - I have no idea when these eggs will hatch

[EMMomma]

Hello,
Longish post ahead:
I have never incubated eggs before. We got a Nuture Right 360 at Christmas time, but then when spring rolled around I got some turkeys and decided not to incubate chicken eggs.
In the meantime, one of my hens went broody. We decided that if we weren’t going to have to do the work, we’d just let her have some eggs. She had been sitting on them for a few days, and on April 30 we marked the eggs we were leaving her, since she continued to steal eggs from other hens.
Fast forward to yesterday. I’m thinking we could have chicks any day, so I go out to the barn and check, and there a huge rat snake on the nest instead of my hen.
I wait for my DH to get hone to deal with it, and then mama hen has no interest in getting back in the nest. She seems afraid - maybe the snake struck at her when he went robbing.
I took all of the remaining eggs out of the nest and assumed they were done for because the snake had been blocking her from the nest for hous. Only 4 left with the marks from April 30. I decided to candle them to see if I could tell if any had been developing before this incident. To my surprise, 2 of the 4 marked ones had movement!
I cupped them in my hands until my husband could unpack the incubator and plug it in. Candles again today and there is still movement!
My dilemma - I have no experience with incubation, and I don’t really know how far along these eggs are. I know I’ll need to do a lockdown where I increase humidity and stop the turner, but I’m not sure when. Based on when I marked the eggs it could be later this week, or sometime next week, but I just don’t know. Is there anything I should see or not see during candling that would say where they are in development? I’m so spooked about even handling them too much or the wrong way, and with the colored shells it’s hard to see anything.
When should I “lock down”?
Hers some pics for making it through all that:
Mama -

Evil, baby-eating snake -

2 little fighters in the incubator -

 

[JacinLarkwell]

Did you already dispose of the other 2?

 

[EMMomma]

Did you already dispose of the other 2?

Yes. They looked empty. No veins or anything. In the 2 I kept I can see veins and an air sac and occasional movement.

 

[JacinLarkwell]

Ah, okay. I was gonna say sometimes babies dont move noticeably. So your incubator is amazing, almost a plug it in and go. Make sure it's at 99.5 degrees and humidity would be best around 55.

I had almost the same thing happen with a broody (lost the hen though, not just an abandoned nest) and I kept turning the eggs until I saw the airsac had dipped down. Once that happened, I did lockdown and let then do their thing

 

[PRchick]

If they were set on April 30, they should be locked down as soon as possible. They may be a little late because of having cooled off, but this would be day 19.

 

[Weeg]

Nice job saving them!
For the incubator, what temp/humidity do you have it at? Can you post calling pictures? By the size of the air cell we may be able to give you an estimate as to how far along the eggs are, or what day they are on.
AS you probably already know, the bator should be set at 99.5 temp, and between 40-50% humidity, I like to shoot for 48%. The temp/humidly gauge is pretty accurate on the NR360, so don't worry about calibration.
You can candle the eggs daily, but I dont like to candle more then that. Keep up the good work!

 

[PRchick]

Ah, okay. I was gonna say sometimes babies dont move noticeably. So your incubator is amazing, almost a plug it in and go. Make sure it's at 99.5 degrees and humidity would be best around 55.

I had almost the same thing happen with a broody (lost the hen though, not just an abandoned nest) and I kept turning the eggs until I saw the airsac had dipped down. Once that happened, I did lockdown and let then do their thing

Stop the turner and I would up the humidity between 60 and 70.

 

[Weeg]

If they were set on April 30, they should be locked down as soon as possible. They may be a little late because of having cooled off, but this would be day 19.

Thank you, just noticed the time they were set.
When you candled them, did the egg look like this-

If so, your right on track and should lock them down by removing the tuner, and filling the B water trough at the bottom of the bator to raise humidity to between 60-70%. closer to 70% is better, and once the eggs start to hatch, the temp will spike above 70% as the chicks will be wet. Thats completely normal. Your doing a great job!

 

[EMMomma]

Ah, okay. I was gonna say sometimes babies dont move noticeably. So your incubator is amazing, almost a plug it in and go. Make sure it's at 99.5 degrees and humidity would be best around 55.

I had almost the same thing happen with a broody (lost the hen though, not just an abandoned nest) and I kept turning the eggs until I saw the airsac had dipped down. Once that happened, I did lockdown and let then do their thing

I’m so glad the incubator is easy to use the temp is at 99.5 and hasn’t budged. The humidity is at 50, but I have everything set the way it is recommended in the instructions, so I’m not sure how to raise that, until I open the other water reservoir that they say to use only for lock down.
Can you describe to me what I’ll be looking for when the air sac “dips down”? Where does it move to?
Also, is there anything I should be careful of during candling, or can I rotate the eggs freely?
Thanks so much for your help!

 

[EMMomma]

Thank you all so much! I will do the lock down!