It'll be overwhelming at first, but I'm sure that with time, once you adapt to the habits and work situations that you're in... you'll get used to it and work wouldn't be as stressful. It'll even be more fun once the paychecks start rolling in, hopefully ;)
I'd say, give it 2 weeks to a month. If you find that work is becoming more stressful in that timeframe(to the point that you're DREADING having to go), then quit. Either have that talk w/ them saying that you want to part ways, or just say that you'll put in your 2 weeks.
It is good to be independent and have extra cash coming in from at least one source....but so many people in the world are doing jobs that they're not passionate about. It's that, and/or they're not doing jobs that they enjoy at all.
If you really don't need the money, and 2 weeks- a month has passed by, then don't do it anymore. Quit, move on with your life, and be happy :)