Since the D3 timeline is aimed at the Early Decision/Early Action application deadlines (D3s have no NLIs), schools often do this kind of visit in the fall, the coaches consider it a recruiting tool. It's what they say after they've seen you, to express interest - "we'd like for you to do an overnight visit." My son visited schools through September after he had offers of admission support but before committing to one. I highly recommend it, you get to meet players, learn how the program is run, get a sense of campus culture.