It sounds like his times are in the range where coaches will want to be in contact with him. Since his PSATs were good, he should do well on SATs.
The coaches are probably trying to pin down their HS class of 2024 recruits for early admissions right now, but they will be picking up recruiting for your son’s class soon.
Have your son fill out the on line recruiting forms, and then follow up with emails to head coach, sprint coach, and recruiting coordinator (if listed as a specific position). The subject header should be easy for the coaches to interpret. Perhaps include class, event and time. In the email, give events and times, grades (weighted and unweighted), list PSAT scores and when he will take SAT. End with an action item for the coach. For example, what times are you looking for in the 100?