Mormon History, Dec 12, 1845

The apostles begin initiating new people into the endowment ceremonies. For those already endowed, there is a repetition of the ordinances within the Nauvoo temple.

[source: Quinn, D. Michael, The Mormon Hierarchy: Origins of Power, Appendix 7: Selected Chronology of the Church of Jesus Christ of Latter-day Saints, 1830-47, http://amzn.to/origins-power]