Filtering with a looped parameter

Hi All,

I have a data set with dates ranging from the beginning to the end of 2016. I am creating a forecasting model and I want to iterate through the data set multiple times, the first time removing the last 6 months, the second time removing the last 5 months, then removing the last 4 months etc.

I am currently trying to so this using a loop parameters operation and trying to adjust the filter, however I can either not get the syntax right or need a different approach.

Could someone please tell me the exact options to select in the loop parameters tool or a better method

Thank you in advance