I was never a fan of any college baseball team outside interest in how my college team was doing until all my teammates had graduated. When my son got to college ball interest I became a fan of whomever was playing BC. I grew up within walking distance. Instead of becoming a fan of any of their sports I found the smugness of BC people off putting. That said, I have friends who went there.
The only pre college interest my son had was Louisville. He verballed there when he was ten. The thing is, Louisville never knew. My daughter verballed for softball when she was fifteen. My (five years younger) son felt the need to announce his intentions.
My son became a Louisville fan when he got to sit with two pitchers in the stands behind the plate at a Villanova game. They let him hold the gun. They asked him what he thought the pitch was before charting what it actually was.