Dynamics Date Calendar by Visual slicers

I ran that file. It's truncating days dynamically as I select something. 

My Case is bit different. 

For Instance I have a table for Sales data. which has field name [Sales_Date] of multiple years. We have easter date slots (for 30 days each slot) for each year means start date of season  and end date of season. So I created a table as you create with calender function and used union to uniform all years data means  union(calender (start date, enddate),calender (start date, enddate),.....).

Then I created a relationship between date table and sales table. All things working fine at this stage.

Now Next thing is to add a visual if user want to see sales data preceeding N Days and Post N Days with eastern. Like it's 04/01/2019 to 04/30/2019 so user can see data for 03/26/2019 to 04/30/2019 so N Days preceeding 4. because User want to see N Days before easter with easter season. 

Where I used technique mentioned about but It did not work by slicer.

If there is an other work around do let me know If i am using invalid strategy to cope up this issue. 

Thank you