My three RIR girls are 15 weeks old now. I am so excited about getting closer to egg-laying time. Do I need to change their diet in any way PRIOR to that? Right now, they are still getting chick feed and BOSS (as treats). They do have grit available to them. And, will I need to coop them in order to teach them to lay in the nesting box? Right now they free range all day in our backyard. Thanks!