Hi there! It's always hard to tell with a picture instead of having the egg in your hands to turn round and get a proper look at, but I think your eggs look okay. I take it the other pencil marks on the 1st egg are where the air cell was at earlier candlings? It's a good idea to outline them like that cause it lets you see the moisture loss progress through the incubation. If those were my eggs I think I'd want the air cells to be slightly bigger, but what you've got there looks good enough to be just within the recommended 11-14% weight loss range. Good luck for lockdown and hatching!
Edit: If you were worried they hadn't lost enough moisture, you could always 'cheat' a bit by stopping turning them for the start of lockdown, but waiting an extra day or so to raise the humidity for hatching. That's a trick that some people use to get a bit more moisture loss when it's needed. I'm not recommending you do that here, just saying that it's something that can be done.
Well, I know some people who live in humid areas can sometimes have trouble getting their eggs to lose enough moisture and that can be with absolutely no water at all added to the bator! What has your humidity been the first 18 days? And yes, you're right, even with all the good advice in the world there's nothing like experience for learning how to incubate correctly. So much of it is just trial and error and figuring out what works for YOU. Other people's advice won't always be suitable, especially where the subject of humidity is concerned!
It's a good idea to keep notes on each incubation. Nothing fancy, just something simple like checking and writing down the temp and humidity each day, and also number of turns if you're hand turning your eggs. How many eggs you started with, how many were fertile, how many go on to hatch. Then if you get a good hatch, you'll know to do the same thing again, and if you get a poor hatch, you can look back through your notes and try to figure out what might have been the problem.
when i first started up the incubator 4 testing it was natrually 40 so all i had 2 do was keep an eye on it and maybe add a teaspoon of water if it went below 40.i tested for 5days and everything was pretty stable.when i added the eggs it went right up in the 70s,,not sure if this was because of the eggs or the weather as its been very damp here??? it took about a week for me to get it down with advise from byc i emptyed all water &left small heater on to dry out the room air and checked it regular.but since then it has been okay.now im thinking that might be why theres slightly small airsacks?
Well, 40% humidity was a good place to start at. The majority of people will do well incubating between 30-45% humidity. Some people don't get on with those figures, and end up having to go either higher or lower depending on what problems they've had, but they're in the minority. Most people will end up settling on a humidity that's somewhere between 30% and 45%, so there's every chance that your eggs should be okay.
You know, if you want to be very precise about it, for your next hatch you could weigh your eggs to judge correct moisture loss. That's how I figured it out for myself, cause I was never very sure what size of air cell was correct when I was candling. I got a cheap digital kitchen scale and weighed my eggs to make sure they got to a 13% weight loss. After a few hatches I figured out that 45% humidity was what worked best for me, and now I set my humidity at 45% for every hatch and just leave it there. I still weigh my eggs just to check they're losing the right amount, but I haven't had to adjust my humidity in over a year. With my old bator, 40% worked best, with my Brinsea, it's 45%. Not sure why, but that's how it is.