mk, you should have some advice on this. zonk, you might benefit a bit from reading this post by BorgoPo on Third Culture Kids, it could help prepare you. My advice is to speak both languages to your child and get them fluent within each. I have friends that speak both french and english in their household. Their son is 2.5 years old and he speaks in both right now. At times it seems like he is behind the curve from a language development standpoint but I think that in the end it will benefit his cognitive development and being bilingual will certainly be an advantage for him in life.
That's a good point, I forgot to mention that in my comment. Children learning multiple languages do take longer to reach milestones, and they look for a while like they're behind in their development compared to monolingual kids. That's completely normal and nothing for parents to worry about. Bilingual children will catch up and won't be linguistically impaired or anything like that.At times it seems like he is behind the curve from a language development standpoint