At the beginning of recruiting, call your DII prospects once each. If they're willing to play DIII, you'll get some kind of 'backup' message. If they insult you, or don't respond at all, move on.
They'll start dropping sometime on the 2nd day, first to A+ prestige, than A, A-, etc. They'll contact you when they've dropped.
You can speed up the process with 'pulldowns'. Give them enough attention and they might drop to your school early. This is riskier and more expensive but most successful coaches do it. At DIII, you probably only have enough funds to use it for nearby players.