1). Make a list of 10 schools he would want to play baseball at.
2). Take a look at what their recruiting classes look like on PG. If they already have 8+ kids committed it's probably not going to happen.
3). Sit down and realistically decide whether he is good enough to play at the top five or so schools on the list. If you think he's good enough, and they still look to be recruiting hold off until the summer.
4). Decide if the current offer is worth passing up for schools lower on the list
5). Ask: If none of the schools on the list are interested - would you rather attend one of the listed schools as a regular student or play ball at the local school that offered?
As for the showcases. PG Jupiter typically wraps up the fall recruiting season, especially for D1 coaches. Obviously there are some exceptions, but it is never worth the money to not get seen. A poor showing at a showcase might also get him crossed off a few lists as well. If he declines the offer - finish football, take a month off, get up to 100% for opening day, and be healthy come late May/June for the summer season