Pay period start, before first check, on or after cover start - what if that is prior to hire date?

Summary:

We are changing our spending accounts to be taken based on the pay dates during the coverage period, rather than the pay periods during the coverage period. To that end, I need to change the rate start date so the deduction is taken on the first pay date on or after the coverage effective date - 'Pay period start, before first check, on or after cover start'. Coverage normally starts the first of the next month, but in some cases could start immediately. I tested and that seems to do what I want, but I was concerned