accrual - vacation

Summary:

To optimize your client's vacation management, we propose implementing an accrual plan with the following rules:

Negative balance: In the 30 days (11 months) prior to the end of the accrual period, if there are no other accrued perioAccds, the system will signal a negative balance, indicating the need for adjustments.
Balance accumulation: Open accumulation periods will be accumulated in the employee's vacation balance, with no maximum withdrawal limit.
Priority for older periods: When requesting leave, the system will give preference to the oldest accrual period, ensuring that the oldest days are used first

What would be the best way to create the quick formula?