The 7th Day Adventists said Jesus would return in 1843 but when He didn't they said they made a mistake and it will be 1844. But when that didn't happened they said they misinterpreted the 2300 days to mean return of Christ rather than Investigative Judgment. So now they believe when 1844 came along that meant people would start getting resurrected and judged. Of course there is no support for this because 2300 clearly says that this is the time that is left when the Temple is overrun, sacrifices cease. Where was there a reinstatement of sacrifices in 1844? Silly. Where has the Temple on earth been reoccupied?

Therefore, we can be confident the 2300 days refers to the last 2300 days within the 7 year Tribulation, about 6.3 years. It is the time when the 3rd Temple is completed and will be overrun.

"Then I heard one saint speaking, and another saint said unto that certain saint which spake, How long shall be]the vision concerning the daily sacrifice, and the transgression of desolation, to give both the sanctuary and the host to be trodden under foot? And he said unto me, Unto two thousand and three hundred days; then shall the sanctuary be cleansed" (Dan. 8.13-14).

The sanctuary is finally cleansed because Jesus returns at that time, at the end of those 2300 days. The 7th Day Adventists were right that at the end of the 2300 days Jesus would return, but their error was in changing 2300 from days to years. The year-day theory creates all kinds of problems.

Various other corruptions occur by trying to use the year-day theory,
http://www.conservapedia.com/2300_Da...cy_of_Daniel_8
A Prophetic Day Always Equals a Year - Miller concluded that all prophetic time-periods in the Bible must be reckoned as ‘a day for a year’ since this concept had been proven true in his own lifetime. In the 1840’s, most American Protestants believed the 1,260 years of the little horn power (Daniel 7:25) terminated in 1798 (Editor’s Note: 1,260 years commenced in 538 A.D. at the “Decree of Emperor Justinian” establishing “Papal Supremacy” and lasted until 1798 A.D. when Pope Pius VI[33] received his “head wound” (Revelation 13:3, 12, 14) from Napoleon and was placed under house arrest; having died in Valence, France six weeks after his disposition there.). Therefore, they concluded that the 2,300 days (Daniel 8) and the 490 days (70 weeks in Daniel 9) must follow the day/year rule, too. (Larry Wilson, Day Star Publications, The 2300 Days of Daniel 8:14, July/August 1998 – (Larry Wilson, The Star, 1998)