I’m going to be quite blunt : at birth !
And the idea to start germinating : wayyyy before birth !
Now I understand that Mom and Dad may not know more than their own mother tongue… or that they never thought about helping their child/dren with this invaluable asset of at least one foreign language.
In my family, I got both ends of the scale 😉
My parents didn’t speak anything except French… fortunately they were very good at speaking good French and that was not lost on me.
But for the most surprising reason – being that my sister and I could go to school without any street to cross! – I went to primary school inside a British convent. The teacher were French and secular but there lived British nuns. Curious… but hey… that was a great start for my “curious life.” Very early, my ears got accustomed to hear the British accent – in English AND French words 😉
We had some VERY basic English lessons (on a voluntary basis… which translated into “not many” !)
Then I followed the most normal of school paths. But I liked English and I really aced it. Although I chose a scientific field of studies, I kept my English alive and better at the “Institut Britannique” with the Cambridge certificates and on !
Fast forward…
I married in a “semi American family” and we decided to raise our children in French and English right from the start. Not for family reasons… just because we intuitively knew that English would be one of the greatest – and easiest – assets we could build in our children. The rest of the family never did it… and, too bad, none of them and their children benefited !
OK…
I’m not going to tell you how bilingual our two daughters are. Just one single example :
Julie spent one year at Georgetown University, Washington D.C., for a major in Econometry (the maths for Economy, OMG !!!). She took a minor in Medieval French History… and had she not chosen that odd a subject… her teachers wouldn’t have ever realized that she was French. They didn’t have a clue until she said she would email me in France for some research documents!
Did I make my point…
Oh not yet, actually : how did we do it ?
We were residents in The Netherlands when my daughters were born… and I had an au-pair from Canada whose only duty was to  speak English – exclusively – to them… yes, from birth ! OK, she did help at home too… but actually talking with the girls in English was her first and foremost obligation.
Then, of course, as we moved to Toronto, Ontario… they were more than ready to fit in the kids crowd 😉
Do you realize how important it can be that your children listen to French and later start early to learn it, if possible ?

My Stories in French for Kids program stemmed from that simple fact : a lot of exposure as early as possible is the pathway to the invaluable asset of a second – not so foreign – language in life !