I was a math major before switching to cs. I’d say algebra/algebra 2/trig are the ones you need to be most skilled at the start.

Linear Algebra was quite possible to learn while in college as it wasn’t needed in the first few cs classes (useful for ai/ml/graphics)

After that my favorites were game theory and discrete math. They are quite practical in a way that fills out the way you can reason about the world. Again, definitely not needed before you start school.

I’m still waiting for calculus/ to be useful day to day, but then again I’m not doing engineering/physics simulation software where it is essential.