There's no list or display that measures progress within a tier, and WGT has never published the Scoring Average needed to advance.
IMO, it's not about moving up, it's about playing in the tier that's best for you. Everyone knows, at least those that have been here a while, there are artificial ways to climb the ladder. Those that advance before they are ready, learn very quickly that the lower tiers are not that easy, and there's no going back once that happens.
The important thing is to post all your scores, play all the courses and play (at least some) 18 hole rounds...and be careful about only playing in Country Club tournaments where easier conditions are set by the tournament creator. Do that and your average will adjust to your real abilities, and you'll play in the tier that is right for you.
Joey
Edit: Should have said to be careful about only playing in CC tournaments.