Next time you hatch, remove the turner at day 18. Do not worry about the humidy as in three days everything will be back to normal.
I have hatched (mistakenly) with the turner in. I did turn the thing off at a level spot.
Chciks are pretty resilient.
You really should NOT stagger a hatch. Put the eggs in on the same day, an fertilized egg can be at room temp for 5 days at least before you put it in the bater. Just keep the little side pointed down.
You are doing great.