You can quit turning. Chicken eggs really don’t have to be turned after 14 days of development. Turning early is important because that is when body parts are forming. Turning helps them form in the right places. Also you don’t want the yolk or developing chick to get stuck to the inside of the shell. By 14 days the body parts have formed and a membrane has developed around the chick (the same membrane that can cause shrink-wrapping) to protect it from coming into contact with the shell. Traditionally we keep turning until lockdown. It doesn’t do any harm and it’s easier to have one date to do all that stuff.
I’d raise the humidity when the first egg needs it. The humidity controls how much moisture the egg loses during incubation. You want it to lose enough moisture so the air cell is big enough for the chick to learn to breathe air before it external pips but you don’t want it to dry out so much it gets shrink-wrapped or doesn’t have enough room to move into hatching position. There is a real wide window that works. You don’t have to be real precise. Lots of people miscount the days and lock down a full day early without causing any problems. The main thing is to raise the humidity before the first egg external pips. If the egg is kind of dry to start with and the humidity is low when it external pips you can shrink wrap the chick. It doesn’t happen that often even with relatively low humidity when it pips but it is possible. It’s good practice to have that humidity up there when it pips. There are no guarantees with any of this. Each incubation is different even with the same equipment and what we think are the same conditions but I think your odds are pretty good with the second egg by raising the humidity to suit the first egg. You are less likely to hurt either egg this way.
Good luck!
