I used the one parent one language method from birth for my daughter who is 7 years old now. She gets Thai from Mom and French from me. She gets English from school, cartoons and games. She is more advanced in English and it looks like her mother tongue is English, perfect prononciation. She is catching up with Thai now, at first she sounded like a Farang speaking Thai! French is weaker because I can't compete with the amount of hours she is exposed in the 2 other languages. A 2 hours per week lesson at the Allience Francaise is correcting this. The vocabulary she has is different for all 3 languages.