Pearce only heard the Spanish version until we found out he had autism, and we abandoned Spanish altogether. Now he hears a little of each, but we mostly ask my mother in law speak Spanish to him because we want him to absorb the sounds and cadences so he can roll his r's when he gets older. We don't expect bilingualism, given that it's sort of wonderful that he's speaking at all. And he's doing superbly with sign language (still learning new signs even though he can talk) so I think we'll teach that to all our kids as a second language instead. Lots of Dr. Seuss books are also really good to sign along with, actually, because they use basic and simple vocabulary and the illustrations are on the minimalist side so it's obvious that [this gesture] means, for instance, BIRD.
We are, however, trying to teach him to read already, even though he's not yet three. It would never have occurred to me to try this young, even though I read exceptionally early, except that he learned four words through osmosis or something so apparently written language comes much easier to him than spoken words. My nephew is the same way; in fact, he was three and a half before he spoke at all and we are pretty sure he could read before then.