I always recommend sticking with it for at least a month or two. Some people might just not want to keep playing after a while. They're just like, "Oh, I don't really care for this," and they move on to a different instrument. Some people just realize that playing an instrument isn't their thing, and that's totally fine. It's okay to not stay with it if it isn't doing anything for you. Just give it 1-2 months to see how you feel, though.