I personally would not lockdown early. It probably won’t hurt but I don’t see anything at all to be gained by that. It’s just not that precise.
Turning doesn’t matter. You can quit turning after 14 days without a problem. It doesn’t hurt them, it’s just not necessary after 14 days.
The humidity is a bit more complicated. You want the egg to lose a certain amount of moisture during the incubation so the air pocket is big enough the chick can pip. Also if it has not lost enough moisture, the chick can be big and soft and not be as healthy at hatch. But after the egg has pipped, you want the humidity high enough to keep the egg from shrink-wrapping. As long as you raise the humidity before the first egg pips but after it has lost enough moisture, you are good to go.
The other reason I would not bother is that last summer I had a broody go back to the wrong nest after coming back from her daily constitutional. By the time I saw her, the eggs were ice cold to the touch. I just stuck her back on the eggs. Not only did she hatch 11 out of 11, they were two full days early under a broody. Hatch date is really not that precise. Don’t overthink it.
