Daniel gives the start time for the 2300-day prophecy to begin, and his contemporary, Ezekiel, gives the day-for-year prophetic time formula which helps us understand that the 2300 refers to a period of years.
Just after receiving the vision of Daniel 8, even Daniel himself did not understand it. The last verse of the chapter says:
And I Daniel fainted, and was sick certain days; afterward I rose up,
and did the king's business; and I was astonished at the vision, but
none understood it. (Daniel 8:27, KJV)
He was apparently sharing the vision with others, but none of them understood it either.
The angel then returns, as recorded in chapter 9, to explain the prophecy to Daniel. At the beginning of the chapter, Daniel starts off with prayer for his people. As he is praying, the angel Gabriel comes to him again--the same one he had seen in the vision.
Yea, whiles I was speaking in prayer, even the man Gabriel, whom I had
seen in the vision at the beginning, being caused to fly swiftly,
touched me about the time of the evening oblation. (Daniel 9:21, KJV)
The angel then gives Daniel the explanation.
22And he informed me, and talked with me, and said, O
Daniel, I am now come forth to give thee skill and understanding.
23At the beginning of thy supplications the commandment
came forth, and I am come to shew thee; for thou art greatly beloved:
therefore understand the matter, and consider the vision.
24Seventy weeks are determined upon thy people and upon thy
holy city, to finish the transgression, and to make an end of sins,
and to make reconciliation for iniquity, and to bring in everlasting
righteousness, and to seal up the vision and prophecy, and to anoint
the most Holy. 25Know therefore and understand, that from
the going forth of the commandment to restore and to build Jerusalem
unto the Messiah the Prince shall be seven weeks, and threescore and
two weeks: the street shall be built again, and the wall, even in
troublous times. 26And after threescore and two weeks shall
Messiah be cut off, but not for himself: and the people of the prince
that shall come shall destroy the city and the sanctuary; and the end
thereof shall be with a flood, and unto the end of the war desolations
are determined. 27And he shall confirm the covenant with
many for one week: and in the midst of the week he shall cause the
sacrifice and the oblation to cease, and for the overspreading of
abominations he shall make it desolate, even until the consummation,
and that determined shall be poured upon the desolate. (Daniel
9:22-27, KJV)
The angel is clearly beginning his explanation by saying he has come to explain the vision Daniel had had. However, the explanation begins with giving an additional time period--evidently the first portion of the 2300 days. This amounts to 70 weeks (490 days), which is further subdivided by sections: 7 weeks (49 days), followed by another 62 weeks (434 days), and then one final week (7 days) which is split in the middle, at the point the Messiah is to be "cut off" (killed)--marked by the cessation of "the sacrifice and the oblation." (At the crucifixion, the veil in the temple was torn top to bottom, putting an end to the sacrificial system.)
The entire prophecy is said to begin with the commandment to restore and rebuild Jerusalem. That commandment was given by Artaxerxes (see Ezra 7). This commandment was made in 457 BC.
Within the following 49 years, the temple was rebuilt--accounting for the first "seven weeks" of the prophecy.
Adding 434 years for the next 62 weeks brings us to AD 27, the year in which the Messiah began his ministry.
Three and a half years later, in the midst of the final week of this prophecy, Jesus was crucified. The week itself ends three and a half years beyond this, at the stoning of Stephen--prophetically marking the end of God's blessings to Israel as His chosen people, and the beginning of the spread of the Gospel to the Gentiles.
So AD 34 represents the completion of the first 490 years of the 2300-year period. The full prophecy culminates in 1844.
The prophecy points forward to events that would take place in Heaven at this time, and not to any specific event that might happen on earth. This is where many have been unable to properly account for it, because they seek for a major terrestrial event to mark the end of this time period.
Remember Gabriel's words to Daniel.
And he said unto me, Unto two thousand and three hundred days; then
shall the sanctuary be cleansed. (Daniel 8:14, KJV)
The earthly sanctuary in Jerusalem was destroyed in AD 70 by the forces of Titus. Furthermore, the Bible has prophesied that this temple would never be rebuilt (many have tested this prophecy, but have failed to build it again). The heavenly sanctuary, however, holds the record of all the sins ever committed; and the end of the 2300-day prophecy reaches to the point in time where that sanctuary begins to be cleansed, as Jesus, our High Priest, enters the Most Holy Place to make atonement for us. This is the beginning of the antitypical Day of Atonement.
The prophecy is significant in giving us an understanding of where in earth's history we are. We are in its final days. The Bible indicates that we will not know the precise time for Jesus' coming again; we must be ready at any hour. But we can know that the time is near.