3 a.m.: I've just put 3 dutch/serama chicks fresh out of the 'bator under a D'anver pullet broody for 7 days only. Will let you-all know if she accepts them in the morning. I'm going to sleep nest to her nest box, in my office
10 a.m.: Edited to include results: the broody D'Anver slept & covered the chicks until about 7 a.m., then noticed she was hungry & thirsty, and she jumped off the chicks,
pecked --at-- them into a corner, and went to the other side of the nest box to eat & drink.
Back she was carried to the coop, and in came the trusty cochin, who is only 7 days broody herself, yet is accepting the chicks, if not thrilled by them. 3 1/2 hours covering them, so far.
Yet another breed stereotype has been reiforced (D'Anver) as with my last broody, a Polish Crested.
Conclusion: Generally, the broody should be near full-term, but there are breed exceptions