I am getting some guinea that will be 3 weeks old when I get them (couple more weeks). We are turning an older chicken coop into a new coop/run just for the guinea. Can they go out in that at this age, or do they need to still be in a box w/light etc? The pen will be completely covered so they won't be able to fly out or anything. They are also the French (big) guinea's. I've got chickens and ducks, but this is our first time with Guinea's - hoping they will keep my garden clean of grasshoppers and such.