Allot 8 hours after 720 hours worked

I have a Vacation allotment plan with a standard years worked/hours alloted matrix:

Year 1 - 40 hours
Year 2-7 - 80 hours
Year 8-14 - 120 hours
Year 15-26 - 160 hours
Year 27+ - 200 hours

Simple setup on the plan accrual matrix. The plan is set to front-loaded, on each employee's anniversary date. That part's working just fine.

We just received a request to add an 8-hour allotment as soon as the employee completes their first 720 hours worked.

I assume that I'll need to create a new plan, run incremental, weekly, and change the allotment to a Fast Formula that looks at their anniversary date and awards the correct number of hours based on years worked.