I applied to PolyU on October 1st, and by November 14 I found out I had been accepted. PolyU included the HK visa application in their supplementary application, so thankfully I didn't need to deal with the visa related things myself, as they handled it for me. Course registration opened in early December, and I was able to choose the number of courses I wanted to take (3-6) and 8 potential courses I wanted in ranked order.

PolyU is a TIM partner school, and only TIM students are allowed to go on exchange with them through MIX. I was able to sign up for 4 SHTM, which is their equivalencies of TIM courses, as well as a Cantonese course.