Zechariah was around in 515 BC and prophesied of the battle to come. 624 BC was before his time. Also, we didn't see the mount of Olives cleave in twain and create a great valley in 624 BC. Obviously it wasn't the battle spoken of.An event prophesied by Christ that has never occurred yet is the following:
Matthew 24:30
30 And then shall appear the sign of the Son of man in heaven: and then shall all the tribes of the earth mourn, and they shall see the Son of man coming in the clouds of heaven with power and great glory.
I am sure that all the tribes of the earth has the meaning of everyone on earth. All those who are on the earth at the time of his coming will see him coming in the clouds of heaven with power and great glory. This same event is described in the book of Revelation:
Revelation 19:11-21
11 And I saw heaven opened, and behold a white horse; and he that sat upon him was called Faithful and True, and in righteousness he doth judge and make war.
12 His eyes were as a flame of fire, and on his head were many crowns; and he had a name written, that no man knew, but he himself.
13 And he was clothed with a vesture dipped in blood: and his name is called The Word of God.
14 And the armies which were in heaven followed him upon white horses, clothed in fine linen, white and clean.
15 And out of his mouth goeth a sharp sword, that with it he should smite the nations: and he shall rule them with a rod of iron: and he treadeth the winepress of the fierceness and wrath of Almighty God.
16 And he hath on his vesture and on his thigh a name written, KING OF KINGS, AND LORD OF LORDS.
17 And I saw an angel standing in the sun; and he cried with a loud voice, saying to all the fowls that fly in the midst of heaven, Come and gather yourselves together unto the supper of the great God;
18 That ye may eat the flesh of kings, and the flesh of captains, and the flesh of mighty men, and the flesh of horses, and of them that sit on them, and the flesh of all men, both free and bond, both small and great.
19 And I saw the beast, and the kings of the earth, and their armies, gathered together to make war against him that sat on the horse, and against his army.
20 And the beast was taken, and with him the false prophet that wrought miracles before him, with which he deceived them that had received the mark of the beast, and them that worshipped his image. These both were cast alive into a lake of fire burning with brimstone.
21 And the remnant were slain with the sword of him that sat upon the horse, which sword proceeded out of his mouth: and all the fowls were filled with their flesh.
These aren't historical events of the past. These are things that are yet to occur. The reason John speaks in present tense is because he is witnessing a revelation and as he sees it he is telling about it. He is simply telling about what he sees in the revelation.
Gog and Magog invaded in 624 BC.