Vesting Period Formula Requirement

Summary: Employee needs to wait for 11 months after enrollment to the absence plan

Content (required): The employee if new hire needs to wait for 11 months, however if it is existing employee enrolled first time to the new absence plan who is staying more than 11 months needs to get total accrual immediately.

The eligibility is Employee and Active status. There are accrual and carryover formula also present. Can anyone provide any sample vesting fast formula to meet the basic requirement?

Thank you

Version (include the version you are using, if applicable): 21C

Code Snippet (add any code snippets that support your topic, if applicable):