Index column based on date, multiple entries excluded based on time

Step 1:

Index =

VAR UserFirstDate = MINX(FILTER('Events Completion';'Events Completion'[user_id] = EARLIER('Events Completion'[user_id]));'Events Completion'[DateTime])
RETURN

DIVIDE (DATEDIFF(UserFirstDate ;'Events Completion'[DateTime];DAY);1)+1

Step 2:

Rank =
VAR d = 'Events Completion'[Index]
VAR c = 'Events Completion'[user_id]
RETURN
CALCULATE (
RANK.EQ ( d; 'Events Completion'[Index]; ASC );
FILTER ( ALL ( 'Events Completion'); 'Events Completion'[user_id] = c ))