Three days before Sunday is Thursday. If you count backward from Sunday, Saturday is one day before, Friday is two days before, and Thursday is three days before.
Sunday
Saturday
TuesdAy
Friday
Three days after Sunday would be Wednesday.
Sunday is 3 days after Thursday.
Friday
monday or sunday
Lent last for 40 days before Easter
Advent begins on the 4th Sunday before Christmas. Lent is the 40 days before Easter.
Saturday.
ThUrsday