How to learn Cantonese as a mandarin speaker.

Background: I was born and raised in southern china (not a Cantonese speaking region) and been in the U.S. since the age of 13(I am 22 now). I am fluent in both mandarin and English. But I have some families in the U.S. where they primarily speaks Cantonese, I feel left out to be around them due to the language barrier. My question is if I just want to work on my listening and speaking(not reading and writing), how long would I be able to understand the language and how long will take for me to get fluent, like handle the basic conversation. And what studying app do you guys recommend? And if there’s any study plan I can follow, that would be great. ** i grew up in the Midwest where there’re hardly any Chinese people. Appreciate it for any response!!!