When does a break start in Washington?

Maybe someone here has the answer, when does my break begin? My partner told me it was when I arrive at the location where the break is taking place, and the company has to provide time to walk there and back, but I don't wanna assert something like that and turn out to be wrong. My managers are already breathing down my neck because I sit down when there's no business, and I wanna be able to stand up for myself effectively when they inevitably get on my ass about it