Changing Majors/Departments at Western (this keeps getting taken down on r/uwo)

Hello!

I am in grade twelve and was admitted into Western Arts and Humanities as well as BMOS. I also submitted an application for AEO status so I am waiting on that too. I was looking through the double majoring options for HBA and I just found out that Western has an HBA/HONOURS SPECIALIZATION IN POLITICS, PHILOSOPHY AND ECONOMICS - POLITICS AND PHILOSOPHY CONCENTRATION (PPE-P) which is literally my dream degree.

I was wondering if anyone knows how I would go about switching from Arts and Humanities to the Department of Political Science. I obviously haven't started at Western yet so I don't know if that helps or hurts an internal transfer. I assume I would have to accept the Arts and Humanities offer first, but who would I contact about making the switch. Would I still have to spend my first year in arts and humanities? Should I wait until after I hear back from my AEO application? If anyone has any experience or advice please let me know!