When you are ready. Learning to drive a car is not about what we as the instructor tells you to do. Certainly our job is assess you and be upfront and honest with you.
Your safety is our primary concern so we are not going to let you go beyond your limits however, you are ultimately the person who must decide when you believe you are ready to progress to each new level.
As an instructor we are constantly talking with you so we can understand where you are and how you are feeling. We are here to work with you in achieving your goals.
We are not here to control you. That is counterproductive.