The broodies I've had have always come out when they chose to, pooped, had something to eat and drink, maybe a dust bath, socialise grumpily with their chums,then back inside. They will stay off the nest for 1/2 to 1 hour, which is fine. If on the other hand we lift them off the nest they will get back inside as quickly as possible. Let her choose the time she wants to leave her eggs, as she will know when they can be left. Does she have free access to her run?