Hi there.

My wife and I only talk to our kids in Spanish (she is from Barcelona and I have roots in Mexico, though I was born and raised in the US), so their first words were in Spanish as babies. Once they started daycare, they picked up the English language like a sponge as a previous poster mentioned. They also watch Playhouse Disney, Sprout, Disney Channel, etc., and don't even speak Spanish anymore unless we force them (pretend we don't understand English so they ask in Spanish). So, don't worry about it. Most schools have ESL, or English as a Second Language classes.

Regards