One who is making progress in Stoicism is called a prokopton. In this letter, Seneca is pleased that his pupil is making progress.
How do you know if you are making progress in Stoicism?
I would say someone is making progress who is first, convinced of the wisdom of Stoicism, second, who wants to put it into practice and third, who ensures his inner dialogue is wise and sound, and that his actions align with his inner dialogue.
the larger part of goodness is the will to become good. You know what I mean by a good man? One who is complete, finished, – whom no constraint or need can render bad. I see such a person in you, if only you go steadily on and bend to your task, and see to it that all your actions and words harmonize and correspond with each other and are stamped in the same mould.