Elvis,
In order to be a head teacher in a Montessori classroom, you do have to complete a certification program, which varies in length depending upon where you take it. However, teaching assistants do not always have to have Montessori training - it depends on the school. Strict Montessori schools tend to want their entire staff to be trained in the methods of Maria Montessori. But there are some, like my school, where assistants may have no training, but are hired for other qualities. For instance, my assistant has no formal Montessori training, but attended a Montessori school from K-8, and graduated from UCLA with a double-major in Education and Music. He could have gotten a job that pays better, but he wanted his afternoons free as he is currently working on a children's music album and also runs a children's theater. Needless to say, he brought a lot to the table that none of the other candidates for his position could match, even the Montessori trained ones. And he makes $1400/mo while working from 8am-1pm every day (from what I hear, though, our school pays better than most comparable schools in the area). Definitely good hours for someone like yourself who wants adequate time to train while generating enough money to live on. Don't just look at Montessori schools though. Most good schools will hire someone with a B.A. to be an assistant without certification, although they may require concurrent enrollment in a certification program.