When I first hired a confinement nanny, I honestly thought one camera in the nursery was enough, but I ended up adding one in the living room too because that's where the CN would sometimes settle the baby during the day. That said, be upfront with your CN about the cameras being there, because a good CN will not mind at all and it actually builds trust on both sides rather than creating awkwardness. I will say the nursery one gave me the most peace of mind, especially at night when I wanted to sleep but still felt anxious, so if you are only going to start with one, put it there first and see how you feel before adding more.