Who says that? Paul? Christ never taught anything like that. Sorry. That's not even how the Church during Paul's time was organized.
God, by His Will has a Plan for every believer
What "Plan?" Where does the Bible mention any God's "Plan?" God is transcendent, all-knowing and needs no planning. And everything God intended to do has already been done. Your God is traveling through time with us.
We don't understand what He wants us to do until we understand His Will and that is reveals to us in Scripture
And how do we know when and what He "wants" us to understand? When it makes sense to us?. Sorry, that is a formula for a man-centered and man-made 'church.'
In order to understand what His Plan is for us, we must first understand what He reveals to us and mature in that understanding, knowledge, and wisdom. That only comes by faith, which is matured as Bible doctrine in our thinking and continually residing in it for further sanctification of our thinking by Him. Every other religion uses the same "reasoning" and their own "holy" books as the basis.
Sola Scriptura as a policy is a safe place to begin
No it's not because it is not even in the Bible. It's a man-made superstition.
Until He has built me beyond that point, I know He has provided Scripture for me to use to understand His Word and grow in Him, so Sola Scriptura for myself is a veritable beginning. The Church pre-existed the Christian canon, even the New Testament. So, nothing could be further from the truth. The life of the Church (liturgical life) existed before the NT was completed.
kosta50: "The Church pre-existed the Christian canon, even the New Testament. So, nothing could be further from the truth."
If you don't find Scripture to be veritable nor to contain the Word, then how does God reveal Himself to you?