.....Having Been Perfected, He Became......(Hebrews 5:5, 7-11)

"So also, Christ did not glorify Himself to become High Priest, but it was He who said to Him: 'You are My Son, Today I have begotten you.' Who, in the days of His flesh, when He had offered up prayers and supplications, with vehement cries and tears to Him who was able to save Him from death, and was heard because of His godly fear, though He was a Son, for He learned obedience by the things which He suffered. AND HAVING BEEN PERFECTED, HE BECAME the author of eternal salvation to all who obey Him."

It sounds as if Jesus had to be fully persuaded (understanding and willing), ready for what His calling was prior to moving forward as Teacher and ultimately the Lamb of God. Scripture reads that He was PERFECTED, made mature and complete, empowered by what He learned in/through the things which He suffered. I would say this suffering was before the cross, experiencing the wickedness of men in the face of the righteousness of God. For the saint of God in Christ Jesus, suffering with Him (Romans 8:16-18) results in glorification together (with Him is implied), as Paul had written. 

In the epistle to the Philippians, third chapter, Paul writes that he is willing to count "all things loss FOR the excellence of the knowledge of Christ Jesus my Lord, for whom I have suffered the loss of all things, and count them as rubbish, that I may gain Christ, and be found in Him, not having my own righteousness, which is from the law, but that which is through faith IN Christ, the righteousness which is from God by faith".(v.7-9)

Paul writes that he has not "already attained nor is already perfected" but presses on. This could refer to v.10,11 where he summarizes what faith in Christ looks like: that I may know Him and the power of His resurrection, and the fellowship of His sufferings, being conformed to His death, if, by any means, I may attain to the resurrection from the dead".  

Jesus fulfilled His calling to High Priesthood over salvation to God through His understanding of what His calling was and willingness to persevere with the Father in it, by the empowerment of the Holy Spirit. To be perfect and complete in this, the believer must "arm themselves with the same mind" (1 Peter 4:1) as He reveals Himself to us.