At Michael’s Signal

But, behold, verily I say unto you, before the earth shall pass away, Michael, mine archangel, shall sound his trump, and then shall all the dead awake, for their graves shall be opened, and they shall come forth – yea, even all. Doctrine & Covenants 29:26

Jesus was the “firstfruits of them that slept” (1 Corinthians 15:20). After he rose from the tomb, the righteous dead from the days of Adam to the meridian of time came forth from the grave (Mosiah 15:21). The first resurrection will resume when the Savior returns to the earth in power and glory. Michael (or Adam, the Ancient of Days) has been delegated “the keys of salvation under the counsel and direction of the Holy One (D&C 78:16). Joseph Smith taught that as the father of the human family, Adam (or Michael) oversees angelic ministrations and the proper administration of the keys of the priesthood and the ordinances of salvation (Teachings of the Prophet Joseph Smith, 167-68). Thus, when Christ returns in glory and at Michael’s signal, the graves will once again be opened, the righteous dead will have body and spirit joined forever, and the blessings of immortality and eternal life will be theirs. (Robert L. Millet and Lloyd D. Newell. Draw Near Unto Me: Daily Reflections on the Doctrine and Covenants. 82)