Request for future leave

Dears,

Kindly, i need a help for the scenario below:

- In case that i have a leave type that is accrual based

- The accrual calculation is that each month it is increased by 10 Hours

- Say that an employee that is hired from 1-1-2016 and now we are at the first March so that the accrual balance will be 20 Hours "( January + February) * 10 H"

- And at the first of March the employee request for a leave from 1-10-2016 to 10-10-2016 (Assume that the working hours per day is 8 Hours) so the total hours for this leave is (10 * 8 = 80)

- Now if the employee request for this leave at the first of march the system will not accept it as at the date of request (first of March) the accrual balance is not sufficient although that at the time of leave the accrual balance will be 90 Hours ( 9 Months * 10 H/Month = 90 Hours)