Priesthood organization came piecemeal

Regarding growth of offices in the Church, President Joseph Fielding Smith taught:

"After the organization of the Church, proselyting commenced and the Church grew in numbers, in spite of bitter opposition and persecution, for all sects and parties were arrayed against it. At the beginning two elders could take care of the little flock, but the Lord revealed piecemeal, line upon line, until the fulness of organization came. There was in the beginning need for officers of the Aaronic Priesthood, and deacons, teachers, and priests were soon ordained. As development came other elders were needed to preside over the early branches which were organized."Later there came the need for bishops to take charge of the temporal affairs. The bishop is the presiding officer of the Aaronic Priesthood, whose duty is essentially, but not exclusively, to look after the temporal affairs of the Church. High priests were also ordained, and later patriarchs or evangelists, seventies, the First Presidency – the presiding quorum of the Church – and the Council of the Twelve Apostles. In this manner, in the course of a very brief time, the same organization which existed in the primitive Church was fully established. Branches grew into stakes of Zion. Missions were opened and the word began to be preached with success in various parts of the world.

"After the opening of the dispensation of the fulness of times the Lord made it known that the organization of the primitive Church of Jesus Christ was to be restored. As early as June, 1829, before the Church was organized, a revelation came calling the witnesses of the Book of Mormon to choose the Twelve who should constitute the Council of Apostles. . . .

"It was nearly six years after this revelation that the apostles were chosen. After the return of Zion's camp from Missouri to Kirtland, the Prophet Joseph Smith called all the brethren who went forth on that journey together. From these men who had been willing to risk their lives in the service of the Lord, the Three Witnesses, who were set apart to choose out the Twelve, made the selection of the Apostles. This was on the 14th day of February, 1835, and the men were chosen in the following order:

"1. Lyman E. Johnson, 2. Brigham Young, 3. Heber C. Kimball, 4. Orson Hyde, 5. David W. Patten, 6. Luke S. Johnson, 7. William E. McLellin, 8. John F. Boynton, 9. Orson Pratt, 10. William Smith, 11. Thomas B. Marsh, 12. Parley P. Pratt."

The order of precedence later was changed according to age.