Use ～て初めて when the main clause becomes true only as a result of the first action — typically a realization, insight, or change that was impossible before. In business writing it frames experience-based lessons: field visits, post-mortems, promotions, customer feedback. The second clause almost always carries 分かる・気づく・実感する・見える or similar, so avoid it for mere chronological sequence (use ～てから).