Time to Provide Certification. When an employee's leave is foreseeable and at least a 30-day notice has been provided, if a medical certification is requested by the City, the employee must provide it before the leave begins. When 30 days' notice is not possible, the employee must provide the requested certification to the City within 15 days of the request from the City, unless it is not practicable under the particular circumstances to do so despite the employee's diligent, good-faith efforts.