White hair

I dont know that this helps because my hair is naturally a dark blonde, but i have been upkeeping white hair for about two years maybe a bit less because it was only platinum for a while.  The way that i do it is i use lots of purple shampoo (ive tried a couple)  i did use Wella T18 toner because it was suggested for a long time but i left it for half the time the box said and i was Blueish grey.  The lengths of my hair are white most of the time so when i first do my roots, i do them then only use purple shampoo on my roots and only on my roots. That makes them match the length of my hair.  When i first went white though i did it from red and the process you describe is how i achieved it, patience, bleach baths, and some color remover. 🙂

Getting your roots white will be the easy part, I think you are underestimating how difficult it will be to fully remove the blue/turquoise.
If I remember rightly you have used both the new formula Plum and Turquoise from Directions. It took me a whole year to fully fade directions turquoise (I hid it under lilac dyes hoping the pink would tone it out) and that was the old formula, which was far less sticky.
I am not sure the blue/green fade from new Plum will ever come out fully, I have a feeling it is one of those permanent blues like Ion.
So i would start fading now, and see how light you can get it. Wait until it is super faded before attempting to bleach it. You should be able to get a pastel mint or somewhere close. If you can get it light and even you could go for silver rather than white.

Thank you both 🙂

It's a year till my wedding so got time 🙂 will let this colour fade and then decide, but silver or even grey would be awesome 😀
Will go read the silver hair post/topic ^^

Thank you =^.^=

mmk This is the color it was when I used the toner Just for reference. 🙂