I started Mandarin with DD in K, but that was only once a week. And she got Spanish in school. Now she is in 4th grade and we are in Canada so she has to take French, no Spanish but she has the Spanish background. After grade 8 she can switch back to Spanish and I think the French will accomodate that. And she does still have Mandarin once a week, I am adding a couple privates a month. We only speak English at home. I think that as long as you are consistent and keep it going, language works. You have to have real immersion later on and keep it going. Hence why most Canadians do not speak French after high school, like me. I can barely say any words in French. I had no place to talk French. Learning and keeping are two different things.