Firsty, You will NEVER see a grey hair cause there is no such thing!
Next you will sprout ear hair and before you know it, the hair on your head will vanish and be replaced with hair on the parts of your body where you really dont need hair for any practical reasons. Big toes will grow a crop , they will be protruding out of your nose and sprouting from your ears, inside and out. Pubes will go white and then drop out too btw.
Whether these hairs are white or not will all become totally irrelevant. I do hope this makes you feel slightly better about getting your first white hair Hitler ;-)