I would use a cone, but it is not required. I used to just wring their neck and let them hang until they stop flapping. However, this led to some slight bruising of the skin which manifested itself as a red color, no big deal, you cannot tell once you cook it but it is a less attractive...
I would think that it would be now or at least soon for those birds. Butchering chickens is not hard, but it does take practice and can be a little overwhelming at first if you have never butchered anything. Just have the book or whatever close by, but not too close, and just go along with it.