Unsure how to implement second language

My son is about 14 months old now and so far my wife and I have spoken only German with him. I was raised bilingual myself, English is my second mother tongue and I would like to pass it on to him. I have been thinking about how to implement this for a bit now, as I don’t want to speak exclusively English with him. I am now considering speaking English with him when we spend time alone together, but to have German as the family language when my wife is there, as well as speaking German when we‘re with other people, at the doctor‘s or the like. From what I gather it‘s important to have clear and understandable rules, situations or settings for the child, in which to speak a second language. Would my described approach meet these criteria?