Before you incubate, you could check for fertility by cracking one open. If you search around you can find threads with pictures of fertile yolks so you know what to look for.
When I have to hand turn (I only have one autoturner), I turn them three times a day. The autoturner is nice. Lockdown humidity should be pretty high. I fill all the troughs and add a couple of sponges to try to keep humidity in the mid 70s during lockdown. The sponges tend to dry out, so I broke the rules and opened the incubator to re-wet the sponges whenever the humidity began to drop. I also drop the temperature to 97. Most of us probably worry a little more than we need to about the exact temperatures. Most thermometers disagree by a couple of degrees, so we never really know how warm it is. Last year I had two different types of laboratory thermometers and two of the little cheesy incubator thermometers, and a cheap digital. The measured temperatures spanned over 3 degrees. I ended up keeping the fancy digital thermometer at 97, which was about 99.5 on one of the cheap incubator thermometers, and 100 on the fancy lab thermometer. Even though the digital gave the wrong temperature, it was the easist to read without opening the bator.
Don't be afraind to let them sit longer than 28 days. They hatch very slowly, at least the early ones did. It was almost two days from first crack to hatch for the early birds. The late bird seemed to go from crack to hatch in about 8 hours.
Hope everything works out.
