Salvation occurs in an instant, and so does santification. They are both instant. Yes you can grow in the flesh as you walk with Christ. But you are holy as God is holy He said so in His word. In Gods eyes you are santified now.
Romans 6:6 Knowing this, that our old man is crucified with him, that the body of sin might be destroyed, that henceforth we should not serve sin.
1 Corinthians 6:11 And such were some of you: but ye are washed, but ye are sanctified, but ye are justified in the name of the Lord Jesus, and by the Spirit of our God.
2 Corinthians 5:17 Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new.
2 Thessalonians 2:13 But we are bound to give thanks alway to God for you, brethren beloved of the Lord, because God hath from the beginning chosen you to salvation through sanctification of the Spirit and belief of the truth:
Hebrews 10:10 By the which will we are sanctified through the offering of the body of Jesus Christ once for all.
Romans 6:18 Being then made free from sin, ye became the servants of righteousness.
Romans 12:1, 2 I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service. And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God.
Galatians 2:20 I am crucified with Christ: nevertheless I live; yet not I, but Christ liveth in me: and the life which I now live in the flesh I live by the faith of the Son of God, who loved me, and gave himself for me.
1 Thessalonians 4:3 For this is the will of God, even your sanctification, that ye should abstain from fornication:
2 Peter 3:18 But grow in grace, and in the knowledge of our Lord and Saviour Jesus Christ. To him be glory both now and for ever. Amen.