Help Learning ADC?

Up to this point in my LoL career (Since Xayah and Rakan released), i've only really played jungle. I messed with the other roles to learn the basics but mainly i've played jungle. Now i'm trying to learn ADC so i could use some tips on when to group up with my team, how to know a teamfight's coming, when to ult (I play Jhin), etc.