We don't have formal ranks along the Japanese model, but we do have some rough categories.
First is student. You're a student as long as you're coming to class. Over time you end up doing more - working with beginners, explaining things (aka "your day in the barrel"

).
At some point if the teacher decides you're ready to teach under supervision. With us there was a formal ceremony that went like this:
"Guru, are you taking beginning students right now?"
"Maybe, how come?"
"There are some people down in Portland who are interested, but they aren't ready to drive an hour each way to Longview."
"Do you want to start a practice group?"
"Sure."
"OK. Just bring them up once in a while for quality control."
Some time down the road he'll say "Oliver Shagnasty knows the curriculum and understands how to apply the basic principles. I'm making him a guru in Sera."
Maybe some day a bunch of teachers will get together and say "Guru Shagnasty is really, really good. And he's been doing this since Moses was in diapers. If you get a chance you and your senior students should train with him."
The time between these depends entirely on when the teacher or the group of teachers thinks you're ready. There's no formal requirement.