How long after obtaining a C1 driver's license can one upgrade to a B2 license?

[StJuniper]

C1 driver's license holders must wait for more than three years before upgrading to a B2 license, and they must not have any full-point penalty records in the two most recent scoring cycles prior to application. Important notes: The driver's license must not have records of major or full responsibility for fatal accidents, drunk driving, driving under the influence of alcohol, or speeding exceeding 50% of the limit. In China, a driver's license is defined as: A motor vehicle driver's license is a legal document issued by the administrative authorities, permitting the holder to drive a specific type of motor vehicle after passing the required tests, having studied and mastered traffic regulations and driving skills, and being legally authorized to learn to drive motor vehicles.