DD1 is almost 3 and so far the multilingual thing is working out amazingly well. We live in the US, she speaks English at preschool, DH's other language to him and my other language to me.
I posted here a while ago asking about gender - since English is nongendered I was wondering if/when she was going to figure out how gender worked. She now understands gender, and while she doesn't always get the gender of a word right, it's clear that she knows each word has a specific gender and that adjectives should share the gender of the noun they modify.
She still has absolutely no clue about case though (since English is not explicitly inflected). It's clear she has no understanding of why I sometimes use the nominative form of a noun and other times the accusative. (Possessive she seems to get although she doesn't always form it correctly.) I'm wondering when is a normal age for a kid to pick this up (and obviously it is really different for her than for someone who has community exposure to a case-using language).
I'm not worried *at all* because like I said I am amazed and impressed at how well the language situation is working out so far, I am just kind of curious about other people's experiences.