"The first seal. The first seal introduces the Antichrist (
Revelation 6:1-2).
Not really. The white horse rider is
Christ, with a crown (of His high priesthood) given to Him by God on His resurrection day. Christ and His gospel went forth conquering and to conquer after His resurrection. "We are more than conquerors through Him that loved us", Paul said.
That crown on the head of the resurrected Christ is again showed to us in Revelation 14:14. "And I looked, and behold a white cloud, and upon the cloud one sat like unto the Son of man,
having on his head a golden crown, and in his hand a sharp sickle." This was the newly-crowned Christ having just been resurrected, and who then harvested the Matthew 27:52-53 saints out of their graves that same day.
Daniel 7:13-14 also has the newly-resurrected and ascended Christ being given a kingdom by the Ancient of Days. The Son of Man being given a kingdom means He was given the crown of his high priesthood on that occasion.
We see this crowned, white horse rider again in Revelation 19. It's not the Antichrist. The Antichrist only attempts to
exalt himself - not that he is given a crown by anyone.
Since this first seal applied to the newly-resurrected, victorious Christ in the first century, the timing of that first seal dictates the timing of the rest of the seals, which followed in relatively short order afterward.
The second seal was fulfilled by the Zealot factions that were present in Christ's days, that grew ever stronger in Israel prior to the AD 66 rebellion against Rome breaking out. This was to "take peace from the earth" in the civil war conditions that were instigated by the Zealots against their own countrymen.
The third seal depicting famine conditions in the world was first prophesied by Christ in Luke 21:11, and then repeated by Agabus in Acts 11:27-28, which took place in the days of Claudius Caesar. Periods of famines and pestilences in "divers places" were a feature of the first century, leading up to that most intense period of famine in Jerusalem during the AD 70 Roman siege when people were dying by the cartload.