Blue shampoo

So I have a question. I recently bought blue shampoo. I have light blonde hair and when it gets brassy its mostly yellow but a few bits get orange (barely though)

But I bought the blue shampoo as people said it made hair appear more icy rather than grey or ashy. I usually use purple shampoo but it would make my hair look darker in a way? So i bought blue shampoo hoping it would keep it icy, is that a good idea?

Also would putting blue shampoo into dry hair and then rinsing it be a good idea as well?