Incoming freshman to undergrad, anything I can start doing for IB?

Take an intro accounting course, as well as some finance courses (I'm assuming you'll already be doing this since you're going to a business school). Also read at least a bit of financial/business news everyday, concepts will begin to click much faster and it can be very helpful when you're trying to craft a "why banking" story or just shooting the shit in interviews down the road.

Join the investment/finance clubs on campus. There will probably be several, so figure out which ones are more selective (might require an application/interview) and have older members that are interning/working in the industry and find a way to get in.

Attend networking events and info sessions on campus and try to build a rapport with the people you meet at them. It might take you out of your comfort zone, especially since you'll probably be among the younger students there and you might not want to come across as overzealous, but the upside to doing this will likely be greater than anything else you can possibly do.

Once you've done 1-3, you should be in good shape to focus on securing an internship for next summer. Something related to dealmaking would be best (i.e. banking, PE, VC, corp dev), but for a rising sophomore even tangentially related experiences (i.e. wealth management, corp fin, accounting) will suffice.