The knees are no longer sore so a bit more rest must have helped. I walked instead of ran, then yesterday ran (w2r2 yet again) with no knee trouble.
As recommended by others, am taking it slowly and gently (sometimes running slower than walking!), running on grass, listening to my body, stretching. Just beginning to do some lunges but not sure I'm doing them right. Will check. Will move on to week 3 when I feel ready.