Christ was the first fruits of the resurrection, the first fruits of them that slept (see 1 Corinthians 15:20). There was no resurrection from the dead, no raising of the body, no inseparable union of body and spirit, until the Lord of Life took death captive and placed all enemies under his feet.
Death was the last enemy (see 1 Corinthians 15:25-26). Though individuals were forgiven of sin and reborn into the family of Jesus Christ long ages before his atoning sacrifice was a historical reality, there was no resurrection from the dead on this earth until his own. His rise from the Arimathean’s tomb initiated what we call the first resurrection.
That first resurrection will resume when he returns in glory and will continue throughout the Millennium. During that time all the dead who have qualified for either a celestial or a terrestrial inheritance will come forth. After the end of the thousand years the second or last resurrection will take place- the resurrection of those who inherit a telestial glory, as well as those who inherit a kingdom of no glory, the sons of perdition.