I am no expert and can only tell you about my own experience... but I moved my chicks out to the coop at 2 weeks old and the nesting boxes were already installed and none of them have ever tried to sleep in them. But they just did that on their own, so I'm not sure if it could be a problem. I just gave mine lots of perches to use and they LOVED those from the beginning... different heights from one foot to about 7 feet high... 1 inch wide, 2 inches wide, 3 inches wide.... they jumped all over those and sleep on them. They played around the nesting boxes from the beginning but never slept in them. Now they are 23 weeks old, laying in the boxes, and doing really well!