Hide time on worksheet

I want to hide time periods that are showing on a worksheet and only show current and future periods. 

The reason I am currently having to include past time is because of a series calculation. 

I have a series (call it Series A)  that is based on another series (call it series using the value of series B, 24 months prior.  Client expression SeriesB[-24].   

Note that series  B is calculated at worksheet time too.

Series A client expression            Series B[-24]

Series B client expression            calculated based on another saved series ex.  sum(nvl(branch_data.dmd_lg1_r,  0 ))

The only way to populate series A is to also include series B and increase the time period on the worksheet to include data 24 months prior.