What you call 'prevenient grace' I call regeneration. We may disagree on its extent and efficacy, but it is the same thing in general function.
Here's a start:
John 1:12 "to those who believed (past tense - condition precedent -- antecedent event) in his name, he gave (consequent event) the right to become children of God—".
Exactly when were they given the right to become children of God? Was it before they believed or after? What does it say? If what you claim is true the verse is backwards and should read: "those to whom he gave the right to become children of God, he then caused them to believe.
Gal 3:2 "I would like to learn just one thing from you: Did you receive the Spirit by observing the law, or by believing what you heard?"
Did these people receive the Spirit before believing or after? If before, then why didn't Paul answer by saying something like, "Neither! I received the Spirit before I believed. I didn't receive it by observing the law nor by believing!"?
Ac 2:38 "Repent and be baptized, (condition precedent) every one of you, in the name of Jesus Christ for the forgiveness of your sins. And you will receive (consequent event) the gift of the Holy Spirit."
Now, did they receive the Holy Spirit before they believed or after?
Ga 3:26 "You are all sons of God (obviously through the new birth) through faith (condition precedent) in Christ Jesus,"
If a person is born of God through faith, then how could a person be born of God before believing?
Ephesians 1:13 And you also were included in Christ when you heard the word of truth, the gospel of your salvation. Having believed (condition precedent), you were marked (consequent event) in him with a seal, the promised Holy Spirit,