Punctiliousness is the noun: the quality of being very careful to behave correctly and follow rules, including the small ones. You might talk about someone’s punctiliousness about titles, or about the steps in a process. It is formal. Like the adjective, it can be admired — nothing is slipped — or felt as stiffness, when the rule seems to matter more than the person. It is not the habit of being on time. That noun is punctuality.