When does this take place in the life of a Christian,
before or after you believe in your heart that God raised Jesus from the dead and confess that Jesus is Lord?
Except a man be born of water and of the Spirit, he cannot enter into the kingdom of God.
I would say that it is neither before or after that someone is born again, but rather at that exact moment with perfect instancy that someone is born again.
How do I know? Because if you are able to confess Jesus is the Christ come in the flesh (and sincerely believe it of course, not just say the words) then that is proof that your spirit is from God and is therefore born again.
1 John 4:2
2Hereby know ye the Spirit of God: Every spirit that confesseth that Jesus Christ is come in the flesh is of God:
The question, then, can you confess that Jesus Christ has come in the flesh?