TSG transition from older youth to adult

What are the principles and the process to transition a near-adult child to actual SELF-government only (and thus wean off of a parent-directed government of self)? Is there a way to quickly transition into only natural consequences and not be dependent on consequences that require a parent's observation and correction? How do you transition towards entirely adult consequences and the relationship we will have at that point? It doesn't seem like I would one day do the full TSG approach with a 17.5 y/o, and then the next day say, "OK, you're an adult now, no more corrections or roles plays or extra chores or Rule of 3, because adults don't do that."

I am aware of the "graduation from extra chores" idea for a youth who has mastered self-government, but what about when time left at home is short and they haven't entirely mastered self-government yet? There has to be more than just graduating from extra chores. Do they also graduate from the role play and practicing part of a correction at that point, too? Or does the role play / practicing part of a correction stop even earlier than that with older youth? How and when do you graduate to giving wisdom and advice only and letting them make their own choices, instead of expecting them to practice and follow through next time with what you said they "should have done" when you corrected them (because that's essentially giving an instruction and they should technically earn a consequence if they are not going to do what you say they should)? How do I give a correction to an older youth, but also give them the latitude to make their own choice (without it being considered disobedience and without experiencing parent-enforced consequences), so they can feel empowered to think through and/or truly choose for themselves (without being motivated by extra chores)?

So how do you transition your TSG / parenting approach for an older youth who is close to leaving home? With limited time left to master self-government, it feels like it would be appropriate to shift to more natural consequences the closer they get to leaving home (even if they haven't entirely mastered TSG so that they can learn real consequences when they are in our home and have more support to recover from them), and to expand their ability to make choices (and potentially fail!) without synthetic consequences always attached.

Please help me know how to navigate this. Our daughter turns 18 in January and leaves home next summer.