How do I drag myself out of sin and back to prayer? How soon can I ask for God's forgiveness?

After we sin, our hearts freeze. For a while, we stay away from God on purpose. We need time to heal, we need some sort of ritual of cleansing, some manner in which to make ourselves (in our own eyes) acceptable again to God. But the way back to prayer must begin as soon as possible, if possible even during the act of sin itself. The sooner we turn ourselves back to face Christ's Light, the sooner we shall drag ourselves out of the depth of our fall. Remind yourself of those who were waiting in the darkness of hell for Christ's Descent - ask for their desperate desire to be forgiven, pray for their unceasing hope that Light WILL one day find them and bring them back to Life out of the death of their hell. For those who put their trust in Christ, there is always Hope, there is always Love, there is always a way back to repentance and Life.