Setting sick plan rollover date to the first of the month

We had a union request to move associates' annual sick accrual to the first of the month of their anniversary date. I wrote the following fast formula, changed the Anniversary Event Rule to Formula, and set the Anniversary Event Formula to my new formula (see fast formula below.)

The annual accruals are now occurring on the first of the associate's anniversary month, as desired. However, the sick plan balance is still rolling over to their sick bank plan on their actual anniversary date, which then zeros out their sick plan balance.

How can I get the annual rollover to trigger on the first of the month (or one day previous?)