The
past perfect is a
verb tense which expresses an
action which was completed before another action or
moment in the past.
Examples:
Until last week, I had never thought about him.
His erection had already subsided by the time his aunt got in the car.
When you arrived, we were unclothed. You had forgotten to knock on your mother's door.
Of course, if you use the words before or after, you don't need to use the past pefect.
You can, but don't feel obliged.
Examples:
She had noticed before I had a chance to hide them.
She noticed before I had a chance to hide them.
After the wall had fallen, we celebrated.
After the wall fell, we celebrated.