data transformation for Sankey chart

I am trying to build a Sankey chart based on my data 

I want a user to be able to select dates using a slicer and see where the customers have gone from / to over that date range

my data is stored in the following way:

so if a user selects 2nd Jan and 25th Jan using a slicer - I want a table to show 

The equivalent in TSQL is

SELECT Isnull(s.current_status, 'New') AS first_range, 
       e.current_status AS second_range, 
       e.customerid 
FROM 
      (SELECT * 
          FROM customer_journey 
          WHERE dates = '20180102'
      ) s 
 FULL OUTER JOIN 
     (SELECT * 
         FROM customer_journey 
         WHERE dates = '20180125'
     ) e 
 ON s.customerid = e.customerid 

I think I need 2 tables and then link them using the customerid so I can do a measure showing the numbers but cant seem to create the tables...

cheers

Kevin