Go to or call the school you'll be attending and talk to the coach or Athletic director and find out what is expected, you have likely missed an opportunity to play summer ball with them already (Many HS's use this to "pre-try out 8th graders). You wouldn't be the first freshman to make varsity but it is rare, it really depends on the game you bring and what the coach sees as your capabilities.
Generally speaking schools will have about 3 days of try-outs, do a cut and then possibly one more cut prior to the season.
Work hard, focus on what you bring and not worrying about the others, relax, enjoy yourself, hustle every time..even when you think no one is looking...it isn't corny...hustle has gotten more kids chances than you can imagine.
Good luck to you!