Contact coaches now. Coaches do a lot of recruiting junior year; D1 coaches can contact players as of 9/1 of junior year, but often watch players the summer before. I think D3 could contact earlier. Send video and Email with SAT/ACT scores, GPA, any major tournament wins. My son knows someone who plays for Wheaton in Illinois and likes it. At D3 schools, students may have to provide some of their own tennis equipment. Unlike D1, schools dont necessarily supply strings, shoes, racquets, etc. Not all D1 schools provide racquets! Since D3 only provides merit and need-based aid, you will want to prepare for Dec/Jan etc ACT/SAT tests to maximize scores and aid. It looks like the higher players on the lineup at Wheaton are 9.5+ so maybe reaching 2 stars and at least a 9.5 UTR should be your goal. The guy my son knew was a 2 star.
Definitely contact D3 coaches in fall before the busier dual season starts in Jan/Feb. Maybe include your tournament schedule if you play any tournaments within a several hour drive of colleges of interest. I dont know how much D3 coaches travel. D1 coaches travel a lot, and usually watch US recruits at more than 1 tournament. I know the coaches of the top D3 coaches do travel to national tournaments, but I dont know the range of travel for the rest. My son got a lot of Emails from D3 coaches but because he wanted to play D1, he didnt follow up with the D3 coaches. Good luck.