Salt Lake Recorder's Land office records place him in the Valley in 1848 when he filed for a residential lot. His name and that of his his wife and a 7-year-old son (George) also appear on a non-contemporary list in Journal History (Supplement after 31 Dec. 1848, 19), indicating they were with him in the Valley in 1848. However, it is highly unlikely that they traveled with him to Utah in 1848.
Justin came to Utah alone in 1848, filed for a lot in the city, and returned to Winter Quarters to retreive his family. They all traveled back to the Valley together in 1849.