What a cute baby he is! Hi, and welcome. If he is turning grey, his color is already changing...and changing color is normal. He may also be losing his puppy coat...not sure if it should come out in clumps because I have not gotten a
purebred Yorkie as a puppy...only a Yorkie-Poo and his hair was silky Yorkie-type hair but did not fall out in clumps. Brody and Mia I got as 14 and 17 month olds, respectively, but Brody did lose his topknot all at once when the darker tan started coming in after the platinum blond...he still had some silver as well.
As far as when to start having him trimmed, I would think that would be your choice. Getting him used to it early might be a good idea. If his puppy coat is changing...which is likely...and he is matting badly, maybe you want to help him out with a trim to minimize his discomfort by you having to brush out tangles.
I am sure whatever you decide to do will be fine...he will grow out again and you can change his coat style if you want. If he stays cottony, you will probably want to have him 'styled' to minimize matting...I understand that is a drawback to the 'cottony' coat...I have no experience with that coat...my kids are silky.
