How long is enough to quit your part time job?

I’m 20 and I just got hired at my first job. Before I get judged I know it’s late for me to only start now but I started late because my parents never wanted me to work during school even though I wanted to. Also, I’d get paid by the navy to go to school so money was never an issue and I never had to ask my parents to help me pay for things. This summer however I was eager to get some experience but it sucks because after months of searching I only just got hired a month before school starts and I don’t really want to work during school especially now that I’ve transferred to a university from cc. What’s the shortest you’ve worked at a place? I don’t plan on staying too long but I also want to leave at a reasonable time , not too early.