For people who actually know what they're talking about when it comes to hair?

I have very brassy blonde hair. I'm so sick of going to the salon and paying so much money to get ash highlights put in, only to have the ash fade within a week and brassiness takes over my hair again. I'm a broke college student and I'm using box dye now to dye my hair a light brown, however I want to use a toner to eliminate as much brass as possible to my light brown doesn't turn orangy. Do I apply the toner before I dye my hair or after I dye it? How long should I wait in between the toner and dying? And what toner do you recommend? Thank you