About day 18 you want to have everything ready for the hatch, what ever position the eggs are in leave them there ( I leave them on their side), no more turning. Also bring your humidity up to 65% or so and then close the lid and leave it closed.
If you open the lid and drop the temperature and humidity durring this time it can harm the hatchlings.
Lid should stay closed for 2-3 days after the first hatch out. They don't need food yet as they will be absorbing the yolk sac.
If you absolutly must open the lid, make it quick and get done what you need to then a quick mist of water before you close to help bring the humidity right back up ASAP.