The ask, after every milestone
Discovery flight, first solo, checkride pass. Each one triggers a text and an email with a direct link to your Google review form. The CRM sends it within a day, while the student is still telling people about it. Instructors get a card to hand over on the ramp for the students who prefer to be asked in person.
Milestone asks produce more reviews than a blanket request. The reviews they produce say what a prospect wants to hear: what it felt like to fly here.