Urgent replies needed please

I'm usually the "slap it on and if it looks a bugger slap another colour on top kinda gal 🙄.
However, yesterday I used a (jerome Russell) bleach kit for the first time ever to remove months of brown colours which I had been trying to strip with dandruff shampoo etc.
I have a short undercut pixie style and my roots are the perfect white blind, but the rest of my hair is worzel gummidge yellow.
My aim was to use schwarzkopf live xxl purple punk temporary/semi permanent (washes out in 15 washes) but am now worried how it will take on the yellow bits.
If I use a toner to get rid of the yellow can I colour straight away or do I have to build up the toner
OR any other solutions.
Thanks guys