“Whom the heaven must receive until the times of restitution of all things, which God hath spoken by the mouth of all his holy prophets since the world began.”
King James Version (KJV)
3:21 Till the times of the restitution of all things - The apostle here comprises at once the whole course of the times of the New Testament, between our Lord's ascension and his coming in glory. The most eminent of these are the apostolic age, and that of the spotless Church, which will consist of all the Jews and Gentiles united, after all persecutions and apostacies are at an end.
Ac 3:21 Whom the heaven must receive. Until all the work predicted by the prophets had been accomplished. The times of restitution. The "restoration" (Revised Version). The moral restoration of the world. Christ will come in person, not before, but after the millennium is ushered in (Re 20:11-15).