I also have a "McMurray Mystery" chick, but they just arrived this morning with our meat birds. I know which ones are our Cornish x and which are the Pioneers, but we have one little chick that is black. I added pictures, but as a day old chick I'm not sure it will do much good trying to figure out what it is. How old should it be before we start trying to guess what it is? This is the first time we've had a mystery breed and not known what kind of chicken we were getting, so I'm at a loss as to when we start trying to guess. Thanks in advance!