We arrived in the U.S. from Israel when our son, G., was 3. He was a monolingual Hebrew speaker at the time, and was already very "into language," speaking at a nearly adult level, so it's been quite easy to maintain it. We've been here for 1.5 years, and he reads and writes in Hebrew, and shows no signs of changing the status quo at home.
He could be considered a "sequential bilingual," but it's been a slow process, since he's been in a bilingual preschool and basically hasn't had to learn English beyond a basic level.
His mother and I both happen to speak English fluently, but never use it at home. G. also sounds out words in English and reads quite well, but he's clearly going to need to catch up with his peers in kindergarten next year. He has an noticeable accent and not too much in the way of vocabulary. We plan to send him to a public school, and I'm assuming they may want to place him in ESL.
I'm concerned about two things. First, we would like to consider having him tested for programs for gifted children, but there's no commonly used battery in Hebrew at this age (we checked with experts in Israel) and in English he's clearly not able to perform at the same level. Second, what should we expect as he enters a monolingual kindergarten? In same ways, it will be the equivalent of coming here for the first time at age 5. Currently there is no pressure on his part to introduce any English at home. So far he's really maintained his identity from "before," which has been nice for us as well. Should we expect him to try to switch to English to be more like his peers? What will help in the transition?