The field is flooded right now, so unless you have experience or some coursework you will get passed over. Sorry to be such a downer, but I'm a school adminstrator and I can tell you that I don't look at "change of field" applicants b/c I don't have the resources to provide training. Please also keep in mind that school districts are laying people off at a very high rate and will be shuffling internally rather than hiring externally.
You may have better luck approaching private schools, as they tend to have different requirements re: experience. They may also have more resources to bring you up to speed. For many daycares, having a B.A. is a turn-off b/c they assume immediately that they can't afford you.
I would strongly suggest taking a few courses in child development and building your volunteer resume. Go volunteer at your children's schools. Write down everything that you are doing- classroom aide, copying, PTA stuff- all of it. These are skills relevant to being a TA- not your background in banking.
Also consider offering your services to the school district during budget time- find out if they need assistance at the schools with an internal audit of expenditures. This process usually starts around now for next school year.
This is not a great time to be entering education... sorry to be the bearer of bad news, but it's a reality. You could also consider pursuing a Master's in School Business Leadership. This would allow you to work per diem or full-time (with school holidays) in the business office.
Look online and find out where your surrounding districts post their job openings. Legally, they have to be posted publically, so find out the website and apply online. A blindly sent resume won't be considered in most cases!