In his wonderful book The Reign of Grace, after giving an example of an experience of a sinner under conviction, Abraham Booth added this footnote, which I find to be very helpful in understanding and acknowledging the diversity of experience among believers in their conversion.

Let none of my readers imagine that the process of conviction here described, is designed as a standard for their experience; or that I would limit the Holy One of Israel to the same way and manner of working on the minds of sinners, when He brings them to know themselves, their state, and their danger.  I have no such intention; being well aware that God is a Sovereign, and acts as He pleases in this, as in all other things.  For though every sinner must feel his want, before he will either seek or accept relief at the hand of grace; yet the Lord has various ways to make His people willing in the day of His power.  Some He enlightens in a more gradual way, and draws them to Christ, by gentler means, as it were with the cords of love: while He strikes conviction in the minds of others, as with a voice of thunder, and sudden as a flash of lightning.  They are brought to the very brink of despair, and shook, as it were, over the bottomless pit.  Nor have we any business to inquire into the reasons of this difference in the Divine conduct.  As the Lord saves whom He will, so He may bring them to the knowledge of His salvation, in what way, and by what means He pleases.  If any one doubt whether his convictions be genuine, let him remember that the question he should ask himself, in order to attain satisfaction, are not: “How long did I lie under them?  To what a degree of terror did they proceed?  By what means were they wrought?”  But, “Does it stand true in my conscience, that I have sinned and deserve to perish?  Is it a fact that nothing but the grace of God can relieve me?  These are the questions which demand his notice, and a suitable answer solves the query.