Our cuckoo Maran is setting on nothing for the last week and one of our Turkey hens has a setting "hobby" I'm not sure her eggs will hatch at all she gets up a lot and spends at least half the day off the nest. I guess it COULD happen but I'm not expecting anything.
I would candle the turkey eggs after about a week/week and a half. It wouldn't be fun if the eggs went bad and broke.