Do you know when the last time she shed?
That might be the best bet you have on figuring out how close she may be to laying eggs if you missed the ovulation.
The twisting she looked like she was doing in the first pic looks like a good sign eggs may be due soon, and the laying in a perfect circle all the time.
Long as the incubator can warm up and get to the right stable temp in a decent time then you can turn it on whenever or just have it on from this day forward until the eggs arrive since you don't know her estimated lay date.