Thanks!
I tried to make it as simple as I could. I did have to explicitly define how initiators were handled by the rule. The way it works now is that any class that counts as full initiator levels (basically any class that gives you maneuvers) doesn't count towards this progression.
The rule is pretty short and I hope it's clear and easily understood. The rest of the document is just links to the disciplines for convenience's sake. I houseruled this with people who had no experience with PoW so I created the document with that in mind.