HI there,
We have tons of Red Tailed hawks in the valley I live in and I free range over 155 laying hens. I have found that having Ancona's atleast help in that they alert the whole flock of a potentially predatious avian threat allowing them to seek shelter. As for how long you need to stay on lock down I would think, once moring comes the hawk will have likely moved on--they get hungry and are not known for sitting around waiting for the prey to come to them--unless---this hawk has been hanging around frequently, a common behavior for females when they have a nest is to hang around or find a dependable source of prey with which to feed their young. But, dpenedning on where you are located and the type of hawk you are dealing with, I would say that nesting time is a while off. Do you still see the hawk?