Oliver H. Olney reports that moving to the Rocky Mountains was a theme among the Saints in Nauvoo in August 1842.
Oliver H. Olney, Journal, August 11, 1842, in The Writings of Oliver H. Olney: April 1842 to February 1843—Nauvoo, Illinois, ed. Robert G. Moore (Salt Lake City: Greg Kofford Books, 2019), 130
As a theme of doings has long ben spoken of for the Saints to arise And extricate themselves by going in to the wilderness with the Natives west As a way is opening for many to start To the Rocky Mountains in order to raise up a Righeous branch the two Prisieners are in alerk [alert?] awaiting the time that they can move together as is said to be the theme.