They don't NEED to come into your home. They may choose to ask to come into your home because they want to talk to you in your comfort zone.
I think the bigger reason is that you cannot make an official visit until their school is in session in the Fall. If they want you badly, they need to get face-to-face with you as early as possible and that may be July. We had in home visits from schools on July 1, July 9 (two), and one in August. Our son had lots of options and so the coaches wanted to wrap it up as quickly as possible. They didn't want to wait until September (we made them wait anyways). They didn't want to wait until "official" visit timeframe.