Welcome to our Arizona thread. I don't know of anyone that is raising Maran's. I have been hatching out baby chick's, but they are the non-white Leghorn's.
The turner should stop 3 day's before the hatch is due. Then the turner should be removed and then you up the amount of humidity. This gets the chick's ready in the right position for hatching.
Good idea about that. At least you do have a rooster to be able to do that with. I'll be keeping at least 2 boy's from the BGD's. I like having more then one roo in case something happens to one, and it's better if they grow up together from the start.