I'm 40 and another one who's been going grey for nearly 20 years already. I've been colouring my hair for fun since my teens but we're past the blend-it-in foils stage and for the last few years I'd reverted to the home colour every 4 weeks but unless I go dark the greys are still fighting through!
I just had ice-blonde foils put in with the plan of growing out to be a "young grey". I'm not sure if it will work as my natural colour grows mousey but goes honey blonde with some sun, so I may need to blue rinse it so I dont just look dirty blonde. Bit scared by the prospect but figure it's the best time to try while 'grey' is fashionable amongst the young whipersnappers.