Good advice from Fred. To add...
Most college RC's will not expect you to know your rotation schedule up front and most will try to connect with the HS coach if they want to see the player pitch in a game. So, don't sweat it until things settle in a bit more as far as which squad and what role he may fill. Once there is some direction there (and maybe when a college expresses this specific interest), it may make sense to have that conversation with the HS coach. Just be very respectful of the HS coach and mindful that his primary focus is the success of the HS team and not trying to coordinate pitching appearances to appease recruiting efforts. Most will do what they can to help and accommodate IF the situation allows. It is also important to them that they help their players with these efforts. If the conversation is handled properly, most HS coaches will be an ally for you. And in a program such as the one you describe, the coach will most likely know the routine.
Side note - if a P is a regular rotation starter or THE closer, then regular season games are feasible. If the P is one of the next few guys, sometimes the Holiday tournaments are when the best opportunity presents itself. If he is lower than that on the depth chart, this becomes a very difficult/unlikely proposition.