Grey HAIR!!!!

I don't think whether you stop hennaing or not will affect how your head will go gray (unless you suspect that there is gray hiding under the henna naturally that you don't know about yet!). 

I don't think gray is so bad personally, especially on long hair, I always thought streaks of it looked nice.  Some of the women in my family got gray streaks around 17 to 20 years old (they aren't redheads)...they often colored it too to their natural color, but it looked pretty neat not colored!  6 is pretty young for gray...are you sure it wasn't just white blonde strands?

Well, my Mum and consequently myself and my sisters all started to grey around the age of 16.  This was no drama for me as I used to like colouring my hair using chemical dyes.  My eldest sister developed a rather large grey stripe in the front of her head following a head injury when she was 6 or 7.  My other sister hit her in the head with a rock and she has never grown any pigmented hair from that area of her scalp since then.  Ppl always thought she purposely dyed it that way, and she really likes it.

Nowadays I use Henna to dye my hair and touch up my roots with the henna about every 3 weeks.  Most of my grey is at the temples and the top of my head (no grey at the back), so if I stopped using henna (not that I ever would, I love it too much!) then I would have grey showing in those areas (and a "delightful" line where the Henna stopped).    Are you thinking of not using Henna anymore? Henna is permanent and will not wash out, so you will have a bit of a line as it grows out.   

Btw, my Mum never dyed her hair.  As I was growing up I remember thinking she was blonde.  She has always had this beautiful ashy colour which is now more of a silvery snow colour. She has light blue eyes and is a well-groomed attractive woman, so her hair suits her. Ppl always compliment her on her hair.   I think that some ppl look lovely with their natural grey (or white) colour showing.   Good on you if you are thinking of going this way!