Bi/multilingual Southperrians.

You guys are misunderstanding my question. If your first language is English, or you were born in a primarily English speaking country, you're not who I'm asking. I'm wondering about immigrants.

Native Vietnamese reporting.

I've always wondered, what language do you think in? All four managers at the place I work are foreign, and speak English in addition to another language. They came from overseas, but have been living here for ages. After using English so much, do you eventually stop thinking in your native language?

I tend to talk to myself (yes I know I'm weird) inside my head, and I have been using English during those periods since around grade 8, when I had barely enough mastery in English to do so. Before that point, I used Vietnamese, of course.
I started English at grade 6, by the way.

That's the closest I can think of as "thinking in English" for now.