Big 4 - jumping from Assurance to TAS as a long-term undergrad intern

I am currently an undergraduate doing a 2 year internship in Risk Assurance. I plan on moving on to another big 4 for TAS after around 10 months, but that is only for an internship which may or may not provide me with a return offer - I want to be conservative and assume the worst. I am asking - if possible - how I can and should move over to the TAS division of my firm from Assurance?

I have read other threads with people saying they have done it, but I am unsure on how to specifically go about this (eg talking with people in the TAS teams - how soon should I express my interest? How direct should I be? How difficult/burdensome is it for them to take me onboard or to give me some experience/opportunities? Should I talk with managers, associates, or even partners?).

Of course, I am prepping my interview and technical skills for IB in general outside of class and work, but I do suspect I will appear as just some IT audit kid. Any thoughts/replies I would greatly appreciate.