We had our then 9 year old and 4 year old start local school with almost no german. Two years later our oldest is fluent in high german but has an accent and the (soon to be ex) kindergartener speaks both german and swiss german beautifully. Kindergarten is especially great for learning the language. It was an ideal learning environment for those in the class new to German.

Choosing local schools is a leap of faith and is certainly not easy but after the first 6 months, language will probably not be one of your bigger concerns.