New buyers analysis per month in a graph

[rafarother]

Hello! 
I had a client bases with all infos and another base with sales. 
I wanna see if a buyer is new or bought something last month. 
I can´t show my dataset, but I have a model:

Client       
                         
 Sales   

Buyers last month is a created column basically: IF((sum(Sales[Sales]), [Last Month Measure]) > 0,01, "Buyer Last Month", "New Buyer") 
When I build a graph with Buyers( a distinct count for Code ins Sales table) in values, date in x axis and "Buyer Last Month" in legend, this is the result:

This is the expected result. 
But I wanna make a dynamic report, that calculate buyers last month/new buyers for each month. 
How can I do that?

[daxer-almighty]

The problem is not clearly enough defined to admit a unique solution.

Please consult this: New and returning customers – DAX Patterns