I use Deva NoPoo
for Blondes, which is a blue-toned NoPoo. My Deva stylist told me to put it in dry hair for about 20 minutes before I took my shower since I was having trouble keeping my white hair white, especially in the summer when it gets yellow very easily.
My hair started going grey when I was about 22. I colored my hair for fifteen years, then transitioned to using toning glazes with low-lights to help blend my white (the front half of my head) with my dark blonde (mostly at the back). I am now pretty much all white. I am 43, but get more compliments on my hair color now than I did when I was coloring. (although I admit to missing the fun of choosing a hair color!!) My hair is so white now, it isn't worth trying to color it.