Ask to be cleansed from sin as you enter the confessional.
Historical edition. Historical claims and instructions are preserved as historical context.
As you enter the confessional, say:
BEHOLD, O Lord, I a vile sinner, poor and guilty and unworthy, come unto thee the overflowing abyss of compassion, that I may be washed from every stain and cleansed from every sin. Amen.