You will know when they are "actually serious"; if you don't, then they aren't. It is said all the time on this board, and it sounds snarky. But, it is true. Until they start talking offers/timing/etc., you have to assume that you are 1 of many (numbers discussed above are likely very close to reality) that they want to keep warm or in touch with. When in doubt, ask. Most of the coaches will be candid. But, listen to what they actually say versus interpreting or spinning it into something you want to hear. Just remember, they probably invite in many dozen if not close to 100 for campus visits / UVs per class. One mid major invited 5 players from my son's travel team and not one of them even came close to an offer.