When does a Born Again person begin to actually reign in Eternal Life with Jesus Christ?

From this world:  From the moment of reconciliation with God. It's your spirit man that reigns in eternal life with God in this world. You begin to live as a Son of God. The scripture states  "To as many as received him, to them gave he power to become the son's of God, even to them that believe on his name." ( John 1:12).

You are able to engage in supernatural activities such as exercising yourself in the things of the spirit without limitations. learning, to live and reign in the dominion and power of God. stepping boldly into God's presence and experiencing his divine presence.  Developing a two way communication with God.  

You are able to grow in the things of the spirit; you can have the authority to cast out devil's; lay hands on the sick for recovery; you are able to receive the holy ghost baptism, you develop the ability to operate in the gifting of the spirit of God; you develop fruitfulness unto good works.

Indeed, you are able to experience a foretaste of heaven on Earth.