hens don't have clocks, they just rearrange things every now and then. if you are using a Styrofoam bater I would recommend putting the eggs in the bottom half of egg cartons to keep them big end up. then place a brick under one side of the bator. after a few hours yo put it under the other side. this way the eggs get sloshed without opening the bator keeping the temp steady.
If resting on their side, place them so the large end is slightly higher than the small end. Draw an x on one side and an o on the other so that when they lay on their side, you only see the one letter (each egg showing the same letter). Three to five times a day, gently roll all of the eggs so that you see the opposite letter. Roll them an odd number of times each day so that their night hours are spent on the opposite side of the night before. The exact time doesn't matter, find something that works with your schedule and can be relatively consistent. Maybe when u wake up, get home from work, and bedtime. For chicken eggs, turn for the first 18 days.
I put mine on a paper towel cut into circles. I mark with a X on one side and a letter or number on the opposite side. When I candle them I right down Egg B has veins/movement ect.
This way I keep track of the good eggs and roll them all to the right side. During lockdown I put the fat end up a little for the air sac.