Columns addition and deletion

Hi guys

How can I have a system where every month automatically 1 columns removes and add extra column. In short I’m trying to create a database which should shows performance in rolling 12 months so I want every month column B removed, shift column C to M in Column B and add another month in column M.

Please help

Thank you

To help myself and others better understand...
You have data in 12 columns.
Each column represents the 12 most current months in order.
At the end of the current month, you want the oldest months data (column M?) to delete and all the other columns to shift over one column, leaving column B empty for the new month?

If you could post an example with fake data with the before and after results "staged", that could be helpful in getting you to a solution.