My 2019 son did Duke camp summer before 9th grade and again winter of sophomore year. (By the way he loved Duke and the camps and got great feedback from them). While he was definitely noticed and even was told by Head Coach and RC that he would hear from them, by the middle of son’s sophomore year they had 10 commits from his class. Unless your son becomes a rock star between soph and junior year, I wouldn’t spend much time with Duke after sophomore year. They tend to be in the early recruiting bucket. Not quite as much as some of the other ACC and SEC schools, but they will have moved on for juniors with the exception of star standouts. And if you’re a parent of a frosh or soph and Duke is high on their list, get to them now. Don’t wait.