No, children do not get confused about languages. Bilingual children speak at least two languages. Instead of confusing the two, they have to learn what language(s) they can use with each person. They start learning fairly early on (before age 2) but this can be influenced by the language situation at home. If some children go through a period in which they mix languages, this is nothing to be worried about. Eventually all bilinguals end up with at least one native language, possibly two. If parents and/or siblings use both languages in communicating with the child then the child will at first naturally assume that everybody is bilingual and that it can mix both languages when speaking with other people. It might take a little bit for the child to figure out that the daycare teacher only speaks English. But eventually it will happen (rather sooner than later). Keep in mind that no healthy grown-up bilingual mixes up languages when speaking to monolinguals.