It helped that we moved to Oslo for a year when Lilly was around 6 weeks; ever since then it's felt natural to have Norwegian be the primary language at home and wherever I am with Lilly.
It's been a little trickier those days I have Lilly's best friend Anna here. When the girls were still one and not big talkers, I used mainly Norwegian still. But when the girls experienced a language explosion after turning two, I felt awkward speaking Norwegian to Anna when she addressed me in English.
A couple of weeks ago, we had some friends over for dinner who'd had a foreign speaking nanny for their child. They highly recommended I try sticking with Norwegian even when Anna was around too.