First of all, I agree with the others that reputation in a school district is very important. If you quit now, you have to realize it will affect whether you ever work in this district again.
I work part time and am always suprised by how part time seems to suck up almost as much time as working full time. I've found that even working part time I have to change my housekeeping standards and budget my time carefully.
How part time? I know I have friends who've been aides and decided it wasn't worth it. Although the hours fit perfectly into the kid's day, often it can be hours like 11 - 2, which realistically mean you don't get anything done while the kids are gone. You have to get used to including your family in chores, taking the kids with you grocery shopping, etc.
However, if you have a job with a better time line, like 9 -12, stick with it if at all possible.
My first year part time was 10-2, but the last two years have been 8 - 12 and it is GREAT!
The first few WEEKS may be overwhelming, not just the first few days. However, some of that is because you are also settling your own kids into school. Extra trips to get school supplies etc. can really add up and make those first few weeks seem extra busy.
Once you settle in, you'll have a better idea of the "fit" of this job. I feel like you might really regret quitting too soon.
That said, if it's not about just being overwhelmed and truly is a fit issue - nasty coworkers, etc. - you are the only one who can make that call.