In this recent question, Matej raises his son English bilingual. I think teaching English very early is a great idea because there's hardly any way around English anyway so you might as well learn it well. I consider good English skills to be essential. But because my family is already bilingual, I hesitate to add a third language at 2 years of age. Besides, I don't know yet how I would do it.
I need some ideas on how to add English into a bilingual family.
Here's my starting point:
My son is learning German because we live in Austria and his mother is Austrian.
Because I am from Denmark and I want him to learn his father's language too, I'm already speaking Danish to him (and no one else is, except when the family comes visiting from Denmark, or when we go there). In other circumstances, I would do as Matej did and speak only English with my son, but I don't want to speak 2 languages with him. On the other hand, I don't know anybody here that can speak English half as good as me.
Television and cinema here in Austria is dubbed, so there's hardly any English to be heard anywhere. Also, there's plenty of literature (textbooks, novels, websites) in German, so there's no urgent requirement to learn English. Consequently, Austrians (like the Germans) are famously and embarrassingly bad at English. (Unfortunately, this includes the average English teachers.) I don't want my son to be that bad at English!
I think English will be taught early on in school, though perhaps not right from the first school year. I can only pray that our local school has a skilled English teacher.
I don't see myself being able to afford English-language private school, so whatever I do needs to precede or go in parallel with normal Austrian school.
We are not planning on moving to an English-speaking country. Our life is here at the moment.
All the household computers run exclusively English software. That's how I learned English to begin with, too: using a text-based adventure game and an English/Danish dictionary. It's not the ultimate solution, but a great start.
My son is 2 years old right now, so I'm not in a hurry to start. I want him to really grasp his two primary languages first. On the other hand, I don't want to wait too long either. The earlier he gets comfortable with it, the better.
I consider my spoken and written English skills to be excellent (for a non-native English speaker), so I am not concerned about teaching "broken English."
(I might add more points later.)