just googled the title-list of all 7 seasons - Edit 1
Before modification by Taiga at 20/09/2012 09:25:42 AM
When you check that list it looks this question is quite revealing as there are only a few names that appear in the titles (Angel, Anne, Ted, Buffy). Maybe the question could be rephrased to when your character first appeared in the series? (answer should be a season then?)