Biographical sketch of Oliver Cowdery has him living in Poultney, VT until "about" 1825.
Andrew Jenson, "The Three Witnesses," Historical Record 6, nos. 3–5 (May 1887), 196–197, 202
OLIVER COWDERY,
Was born in the town of Wells, Rutland Co., Vermont, in October, 1805. He was principally raised in the town of Poultney, Rutland Co., whence his father removed when Oliver was only three years old. About the year 1825, Oliver removed to the State of New York, where his elder brothers were married and settled, and some two years later his father also moved to that State. Oliver was employed as clerk in a store until the winter of 1828-29, when he taught the district school in the town of Manchester, Ontario Co., N. Y. , nine miles from his father's house. There he first became acquainted with the family of Joseph Smith, sen. (father of the Prophet), who was one of those who sent children to the school, and Oliver went to board awhile at his house. During that time the family related to him the circumstances of young Joseph having received the plates of the Book of Mormon. Oliver became deeply ested and determined to find out the particulars about this wonderful event. He also prayed to the Lord to enlighten his mind, and one night, after he had retired to rest, the Lord manifested to him, that he had been told the truth in relation to the finding of the plates. He then concluded to pay Joseph Smith a visit, in order to learn more about it, which he did, and on April 5, 1829, he first met the Prophet at his temporary home in Harmony, Penn., whither he had removed because of the persecutions to which he had been subjected in the State of New York. This meeting of Joseph and Oliver was not only providential for the latter, but also for the Prophet himself, who had already been the custodian of the plates of the Book of Mormon for some time, but had been unable to proceed with the translation for the want of a scribe. In Oliver he saw the proper person to assist him in his work, and two days after his arrival, Joseph Smith "commenced to translate the Book of Mormon," with Oliver Cowdery as scribe. A few days later a revelation was given to Oliver Cowdery through Joseph Smith. (Doc. & Gov., Sec. 6.)
. . .
Elder Phineas H. Young, who was present at the death of Oliver Cowdery, at Richmond, Missouri, March 3, 1850, says, "His last moments were spent in bearing testimony of the truth of the Gospel revealed through Joseph Smith, and the power of the holy Priesthood which he had received through his administrations."