A penny-sized air cell is about right for 4.5 days. A nickel by 7 days, quarter by 10 days is what I go by. Weighing is nice if you can do it safely.
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Third photo looks like a slightly more porous shell, don't make changes based on that egg. Mark the air cells, swap positions in your incubator with your smallest air cells, and check again in a couple of days.
Don't make changes based on the smallest or largest, or eggs that don't show growth. Use the middle 2/3 as your basis, whether weighing individual eggs or candling. Weighing full trays is the most accurate way to determine proper moisture loss.
The eggs are about 4.5 days along. I don't have a scale to weigh them but I will get one before I do this eggain. The humidity has been about 35 percent as recommended. I think I'm going to try and raise it up though.