Most if not all d3 will commit after junior year. You will be on their radar as a soph. The high end d3 which includes all Nescac will want a 3 year grade report and an SAT that qualifies. This will get you support from the coach to admissions if they want you as a player. In most cases do your prospect days in the fall of your soph year and junior year to see where you fit and if your son likes the feel of these schools in this space. The coaches are very up front and will communicate openly. Enjoy the visits. Many of the facilities will impress and surprise you.