I think it was when the school enforced the new Squad scheme.  Shan was originally the librarian, and Vic was the only student for her to mentor.  I think... 

Actually Imma agree with Xerox-kitty. When they made the official squad system, Shan was put in charge of the kids not old enough to be on squads. Anole, being old enough was forced into having a new advisor. I don't know whether or not he chose Northstar but they did develop a bond. we see this when Northstrar is killed by Wolverine and when he is revived, it is my understanding that Anole was over joyed (I haven't read it) to see his former advisor, Northstar attacked him while under Hand(?) influence and they haven't been the same since. When cyclops sent Northstar to speak with Anole during the divided we stand arc, that is why it ended with Anole striking Jean-Paul in the same manner he had stricken him.  
 
after Jean-Paul's death their was a piece of dialogue between anole and shan that suggested that Anole looked up to Northstar because he was gay and an X-Men and that Shan, while a lesbian, just wasn't the same.