I have a few 1 year old hens that we recently adopted. Out of the of the 6 of them only two have laid.....one has laid almost every day for 10 days and the other laid for the first time today. Im not sure if it's stress induced from being moved but when should I get concerned? I read I can put a little bit of apple cider vinegar into their water to help their stress levels. Anything else I should do or look for?