Don't try to quantify it with a specific score: "this score is the magic tipping point from basics to advanced!" That approach makes no sense.

You have to ask yourself - have you MASTERED the basics? I don't just mean have you read the guides and done a lot of problems. Do you have a deep understanding of how the concept it tested, and could you tackle any new problem that tests that concept? Could you write your own GMAT questions for that concept? If so, move on to the advanced. If you're not sure, spend more time thinking about the basics. Not just more time doing, but more time thinking.