How to prepare non english speaking kid for school (Hong Kong)

Hi dear community

My family will move to HK next summer.

Our 4 year old son does speak German. How did your kids learn english? Did you just put them into an international school and hoped that they will cope sooner or later? :-) I am a little bit afraid of doing that, he will understand nothing at all...

Did you prepare your kids with films/books/english lessions?

How long did it take for your kids to get along with the language?

Best regards and wishing you a lovely day,
Denise