I understand how you got here. Life can throw you a few curves occasionally, can't it.
I don't know the right answer. I'm not sure there is one. Your main issues are opening the incubator during lockdown because of the humidity and turning the others at the same time. I would not get overly worried about the high humidity on the late eggs during lockdown. It's obviously not an ideal situation, but I think it is minor compared to the turning and the need for higher humidity during lockdown.
I don't know your set-up, which incubator or whether you have an automatic turner. If you have an auto turner, can you take some trays out? I have that yellow Hovabator turner and it is not hard to take some of the trays out of it. If you can, maybe build a fence from hardware cloth to put down the middle to separate the new eggs from the old, or maybe build a box out of the hardware cloth and put it over the early eggs so they can't get to the turning eggs. One worry on that is that a chick may get a leg caught in the turner. There's probably a small chance of that. A bigger worry would be that the first hatchers will probably mess up the incubator pretty badly. You don't want the mess to start growing bacteria that could infect the later eggs.
So if you have an auto turner and you can take some trays out, your problem is solved.
I have not done it, but some people have built turners they can activate by reaching a rod or wire through a vent hole. If someone has an idea how to do this and can tell you or you are mechanically inclined and can design and build one, see the above idea.
If you do not have an auto turner but are turning them by hand, I'd probably keep turning them until I saw a pip, then just not turn them until the hatch was over. Like I said, I don't know if there is a right answer, but I think you are more likely to do better this way. Besides, the first eggs were the ones you wanted. Anything extra you get will just be a bonus.
