They probably meant before they start learning English in primary school, not before they start school. This used to be the case in the Netherlands too; I pick

They probably meant before they start learning English in primary school, not before they start school. This used to be the case in the Netherlands too; I picked up a significant body of English from British TV series watched with subtitles as kid. Nowadays this advantage will probably be missed by most children, because the streaming services offer a lot of dubbed content, and you get to pick what you watch unless someone guides you. Subtitles can be avoided for longer.