Not in every sport, but generally D3 recruiting is behind D1. There is always a little shuffling that happens both with the athletes who do very well during the state championships as juniors and the coaches who are finalizing their lists, but there are many who are locked in early in junior year.
I don’t think she’ll be missing a chance at a D3 while waiting for D1 schools. If she has a lot of interest from D1 coaches, she’ll feel more comfortable waiting. If not too much interest, she may want to move on to D3.