Even after diving into the first volume of this series I am still uncertain as to whether or not I should have started with the prequel. As I feel like I would have enjoyed it more if I had known the Characters better.
What I can say is that it was a fun read from start to finish, and it didn't feel like their was REALLY anything that would have spoiled the later volumes, or been misunderstood without the context of the future volumes.

I think starting with early registration, or Volume One are both completely acceptable approaches to beginning this series.