I'm also not 100% clear.
But if you mean that the FV needs to be further inflated for a time delay in receiving funds then you could take a 1 month FV of the FV
ie
If you
- receive a 6% return for paying in $100 every year for 10 years and
- this final payment is delayed by one month at the same 6% rate then this calc "rolls" the FV forward by one month
=FV(6%/12,1,0,FV(6%,10,100))
Cheers
Dave