It's good to also talk about failures, so let me tell a failure story. I intended to do this the other way round: I'm a native Spanish speaker with good command of English (officially CEFR C2 level which is the highest recognized in Europe) and I intended to always speak to my son in English so that he could be bilingual (or trilingual, as we also have an additional regional language here).

It was an utter failure. Soon after he was born, I discovered that even though in theory my English skills are good in theory, speaking to him in English would impose an emotional distance. It wouldn't be as natural to express love and affection in English, I felt it would be a barrier between us and I really wanted to be close to my baby, so I gave up.

Then, as the kid grew, and as a plan B, I learned that some parents used the strategy of using English in a specific situation (a given room of the house, time of the day, etc.). I first used it in the kitchen, but then my parents (my mother doesn't speak English) moved to live with us because circumstances, so it became very awkward and I stopped. Then I decided to use it in playgrounds instead. But as my son learned to talk and express himself better, he started to get angry. He would say "¡En castellano! ¡En castellano!" ("In Spanish! In Spanish!"). I tried to convince him, but he is very stubborn, so I mostly gave up because otherwise he was always angry with me in the playground.

So now (he is 4 years old) I just try to tell him things about English sometimes, read some stories in English to him (but not too many because he gets angry and demands "en castellano"), and things like that. I hope he will still learn English, like I did, but the bilinguality plan failed.

Big respect and kudos to those who manage to keep it up!