Your cousin is starting to calm down after talking to you, but you can tell she still has one big issue on her mind. Her husband is bilingual and has been speaking to the baby in both English and Lithuanian (his native language). Your cousin wants the baby to learn both languages, but thinks they should wait until the baby is older and has mastered one language before exposing him to another.

What effects (positive or negative) would it have on the baby's language development (in English and/or Lithuanian) if they exposed the baby to both languages right now? [1] What about if they waited until the baby was in elementary? [1] Make reference to specific effects associated with different age ranges in your answers.