Baptism (by immersion) is a one-time act of obedient identification with Jesus as Lord. A believer is baptized as an outward sign of his or her conscious confession of repentance and faith to Jesus Christ. It is a beautiful picture of the believer's death to sin, the burial of the old life, and the resurrection to walk in newness of life in Jesus Christ. Mark 1:9; Matthew 28:18-20; Acts 8:38-39, 2:41; Colossians 2:12
Baptism doesn't make you a believer – it shows that you already believe. Baptism does not "save" you, only your faith in Christ does that. Baptism is like a wedding ring – it's the outward symbol of the commitment you made in your heart.
As soon as you have made the decision to exchange your life for the life of Christ you can and should be baptized. If you wait until you are "perfect", you will never feel "good enough!"