Ours has been in the coop for about 3 weeks. It looks slightly darker, I think, and of course there's poop in it. They spend most of their time outside. So anyway I've read that people throw scratch in the coop to get the chickens to stir up the shavings. When do you do that? Before adding a new layer of shavings? Every so many days? When do you add more shavings? Do you use a set schedule or just wait until it's a certain color, depth, etc?