There are different paths for children becoming fluent in another language.
One path is to grow up in a family where the language is spoken. A nice luxury!
Another path is to live in a country where that language is spoken, going to school and hanging out with friends everyday. Another nice luxury!
Another path is to attend an immersion school here in the U.S. where the language is spoken everyday. Another luxury!
Then there is a more common path - taking classes and/or using self-study programs with the goal of achieving fluency as an adult. This takes time, but is attainable. Think of this path like the student who wants to learn to play an instrument or become skilled in a sport. It takes ongoing practice, dedication, and patience.
If possible, start your child young. Why?
Well, have you ever noticed how people from other countries seem to know English so well? That is because they begin learning English prior to high school. Children possess a greater ability to acquire language more naturally the younger they are.
So, how do you navigate this more common path to fluency? Here is a suggestion:
The more common path takes several years to complete, BUT the goal attainable! Know your gostick to your plan, and go for it!