BROC,
We are also a California family with a 2012 D1 and a soon to be 2016 D3 player. The process was a bit different for each, but there were more similarities, particularly upfront.
Creating a vetted list of target schools, i.e., schools where your son could be admitted AND could play baseball, was a starting point for us. That's the list of schools the player is pursuing. None were a slam dunk for both admission or Spring roster spot, but all were "possible" for both.
Then it's getting in front of those schools (Admissions and baseball staffs), e.g., email, letters, phone calls, showcases, camps, campus visits, online Admissions and baseball profiles, etc. "Demonstrated interest" by the player is very important, particularly for a player who's not a "must have" talent. Now is a great time to start for a high school Junior with D3 schools.
My 2016 had a dozen D3 coaches offer him a Spring 2017 roster spot. He turned down 5 of those schools and applied to the remaining 7 (1 ED, 5 EA, 1 RD). Despite support with Admissions by the Head Coach, he was denied at the ED school which was the biggest academic stretch by far. "Support" doesn't mean guarantee at this level. He's been admitted at all five EA schools. He really likes the RD school, but they didn't offer EA so he's in the regular pool.
Had the ED school accepted my 2016, he would've been done with this process in December. If he accepts one of the EA schools, then he'll be done now. If it ends up being the RD school, then he's done in March. The bottom line is your player is roughly 11-14 months from being done with this process so timing is essential to start now.
Also, a 28 ACT (and perhaps a greater score coming?) will open doors for many schools if the baseball talent is there. Higher is better of course.
Best of luck!!!