I am sure you won't like the answer, as it is one I don't really like myself, @Kristine Klein, but it would work like a charm in Apptio BI:

In the Date Range option I found Last 12 Months out of the box:

(Later):
It wasn't so hard in CT, after all:

I Added Months to the Columns and then, in the Range... option:

... I selected Past Range=11, Future Range=0:

I hope this helps, @Kristine Klein.
#TBMStudio