Usually I have her cutscene pop up once I reach the right alignment level while I'm still on Citadel station, but with one of my latest play-throughs I believe I was still rather neutral and I got it when I was leaving the Polar Academy?
[edit:] Found this in aeon's nice KotOR FAQs:
Visas will show up even if your character is neutral. The triggers for her appearance are:
* Your character's alignment is 50% light or dark. That means halfway to either LS or DS mastery, or
* Your character has gained a combined total of 50 LS or DS points, or
* Your character has met at least 3 of the Jedi masters. I think Vash counts, even though she is dead when you find her. (Neroyume)