SUM data between two dates excluding weekends

hi. i want to sum across the next 5 working days 

5 days added to the date 4/8/20 is 9/8/20 so excludes the 10/8/20

I have a dim_date table with a working_day flag.

Does anyone have thoughts on a nifty way to either move  forward '5 rows" im dim_date and get the date in that row (i.e 10/8/20) OR

SUM across 5-rows ub the fact_data table rather than use DATESBEWTEEN()

thanks