A quality Montessori program has to begin with appropriately train teachers. I would suggest that you go the Montessori School Accreditation Commission and review their standards for schools. They are a new program that will provide accreditation for Montessori schools. Mr. Ball's advice is excellent. The 3 courses I speak of take approx.
Most teachers welcome questions.
My first suggestion would be to discern what type of Montessori school your school is. Some independent schools remain independent for specific reasons. Others simply don't meet the standards. Parents should be aware of and comfortable with the school's position and philosophy. Every Montessori course I am familiar with are one to two years in length.