My parents were first generation immigrants to Australia. My mother had no English when she came here. My father had high school English, but no Australian accent. My parents worked in their fish and chip shop attached to the house, so much of the daytime I was reared by Sesame Street; I interacted with my parents in the evening.
Outcome 1. I did not speak until I was two years old. I presume that was because I was getting mixed English and Greek from them. I was reading pretty early, but not speaking.
Outcome 2. My parents asked their GP what to do about me not speaking. This being the ’70s, the advice was to use just one language (not: one language per context or per parent). My parents (to my surprise now) chose English. Had we not moved back to Greece when I was 8, I would never really have learned Greek.
Outcome 3. I did not really interact with any native speakers of English until I went to kindergarten. Therefore, having been reared by Sesame Street, unsurprisingly I spoke with an American accent. In fact I did not acquire an Australian accent until after we moved back to Australia, when I was 12. My first year back of schooling I was teased a fair bit about the accent.
(Long gone now, though after three years of living in the States at 28, I was starting to do American things with my vocal equipment, and they come back if I speak for ten minutes with an American.)