We live in central PA; every day now is in the 80s or 90s and humid. Our 12 chicks are 4+ weeks old. The brooder is indoors overnight. Any idea how much longer they'll need the heat lamp? Is there a set age where we can turn it off and leave it off, assuming our temp trend continues? Also, is there a common age at which they leave the brooder and go to the coop? Thanks.