I'd rule that if you take a class, to get that -10% karma cost, yes, it reduces that; it does not otherwise reduce the amount of time you have to spend on initiating, on whatever is required for your ordeal, on the amount of time your group might require you to spend doing good deeds in their name, whatever. It's how fast you learn a spell, or gain a level in a skill; that's training. But because other parts of Initiation are (or at least can be) so vastly different than just 'I study and practice', I would give it an emphatic 'only the class time' ruling.