All good stuff, even what the last guy said. Unless you plan on being a career CFI 1500 hours ASEL is the same as 2500 hours ASEL, or 3500 ASEL...
I would tend to explain the entire process (syllabus, PTS, written, checkride) sooner rather than later (but not on the intro flight). That way the student understands the structure, what he's working towards, and how far along he is.