I have table in Power BI with following columns: Country, Date and event. I would like to add measure or new column if needed with 'Start Day'. 'Start Day' assignes value '1' at the first day that value greater than 0 apears in column 'event' and starts counting days from this date. In example below for country UK value 1 in column 'event' apears on 19/03/2020 and in column 'Start Day' value 1 is assigned. Next date 20/03/2020 has value 2 assigned and so on. What is the best way to do this in Power BI?
Robert