Please allow me to clarify putting the chicks into the coop for three hours prior to dark. This is not the same as cooping up adult hens in a coop to establish that it's their home base.
The reason for putting baby chicks in a coop three hours before dark is to allow them to become comfortable in the coop before it gets dark when they would otherwise be afraid discovering themselves in a strange place and it suddenly gets too dark for them to see where they are and if there's anything threatening in there with them.
You will still need to teach them to go into the coop when it gets dark. That is another issue, and it can require a bit of work to accomplish.
The reason for putting baby chicks in a coop three hours before dark is to allow them to become comfortable in the coop before it gets dark when they would otherwise be afraid discovering themselves in a strange place and it suddenly gets too dark for them to see where they are and if there's anything threatening in there with them.
You will still need to teach them to go into the coop when it gets dark. That is another issue, and it can require a bit of work to accomplish.
