I started getting white hair in my early thirties. In 2001, suffered a major back injury at work, after which a whole swath of my hair turned white. Now, at 42, most of my hair is salt & pepper, the beard too. Recently I noticed I've started getting the odd white hair down below.
By the time I'm fifty, most of my head and facial hair should be white thanks to my 1/2 Cree indian grandfather. I have otherwise aged very well, most people who guess my age are about ten years off on the younger side.
I think some white hair looks good on most men; distinguished and handsome.