The first match as soon as you get her by herself aboard the Hawk w00tthe second at level 15 and the third at level And if by bug, you mean the bit where you can be left roaming the corridors of the Telos Academy after Atris' cutscene, then there is a fix at the TSL Restoration Project from this thread here. Make sure you save before you fight her for the third time, because there's a notorious bug here. Only problem is, I cannot convince her to become a Jedi because I need a bit more influence with her, and the only way I can do so is by sparring again.
Just curious - I just finished sparring a second time with the Handmaiden, and have finished all conversation loops that are available to me up to that point with her.