I know I have read diffrent threads about this but...there seems to be a diffrence in time frame...I am thinking of getting 2 more hens today a Buff Oprington and Wyndotte...how long do I have to keep then isloated from my flock? I read 2-3 weeks and then I read 4 weeks....so how long? One of them is almost 1 year old and the other is about 5 months old...