I did that the very minute that he first shows up in the game. It was my first achievement.
Same. I've run into a snag though, I can't seem to figure out how to unlock the "Perform 20 unblockable lightsaber combos" achievement. Tried everything I can think of and nothing has seemed to work.
Also, for the Arcade Master achievement, does it mean win 100 games? Because I've accumulated 100 points over the course of a few games and the achievement has yet to unlock.