The only sin you are born with is original sin, and that is a sin contracted, not committed.

But yes, when you are baptized in the name of the Father, and of the Son, and of the Holy Spirit, you are cleansed of original sin and all sins, mortal and venial, you have committed up to that point. After that, you have confession.

Some of the early fathers, particularly Tertullian, suggested that converts delay their baptisms until later in life (even as late as on their deathbed) in order to ensure a clean soul at the time of death.