According to the verse, predestination has to do with the foreknowledge of God.
Romans 8:29 For whom he did foreknow, he also did predestinate to be conformed to the image of his Son, that he might be the firstborn among many brethren.
When does God know you as a Son?
Galatians 4:
4 But when the fulness of the time was come, God sent forth his Son, made of a woman, made under the law,
5 To redeem them that were under the law, that we might receive the adoption of sons.
6 And because ye are sons, God hath sent forth the Spirit of his Son into your hearts, crying, Abba, Father.
7 Wherefore thou art no more a servant, but a son; and if a son, then an heir of God through Christ.
8 Howbeit then, when ye knew not God, ye did service unto them which by nature are no gods.
9 But now, after that ye have known God, or rather are known of God, how turn ye again to the weak and beggarly elements, whereunto ye desire again to be in bondage?
Now that God knows you as a son, stop placing yourselves back under the bondage of the law.
John 1:12 But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name:
Once you believe on His name, you receive power to become a son of God. God now knows you as a son.