Extensible Documents Time Variable

I have built out an extensible document in PowerPoint that extracts a set at dashboards out of OneStream. I have charts displaying data for the current month, and previous two months. 

I am having trouble using a variable to label the two previous months. For the current month, I just use the |CVTimeDesc| variables and it labels it correctly. But I can't seem to find a variable that works to display the prior period months description. Something along the lines of |CVTimePriorDesc|...

Any help appreciated. Thanks!