Dative and Accusative of Time

Acts 13:20
When the dative* is used for time, it is always viewed as one whole point or object; when the accusative, it is a space during which. Thus, taking the common reading, Judges characterized the period of 450 years, as we hear of them during forty years in the desert. (Ver. 18.) So ἱκανῶ χρόνω in Acts 8:1111And to him they had regard, because that of long time he had bewitched them with sorceries. (Acts 8:11), and Rom. 16:2525Now to him that is of power to stablish you according to my gospel, and the preaching of Jesus Christ, according to the revelation of the mystery, which was kept secret since the world began, (Romans 16:25). Thus τρίτη ἠμέρα and τρίτην ἡμεραν would not have the same force, though in result the sense would be the same. In the first phrase I should think of that one day so characterized. With Τρίτη ἡμέρα. I think of two days elapsed before. In a word the accusative is duration, as the dative is epoch, though in sense running often into one another. Thus according to the common reading of the dative, in Acts 13:2020And after that he gave unto them judges about the space of four hundred and fifty years, until Samuel the prophet. (Acts 13:20), the statement would not be during 450 years, but up to, as far as (i.e., counting from the end of the desert). Thus Joshua, Elders, and Cushanrishathaim would have to be deducted—say some forty-five years. And the chronology is in no way changed. But then the reading of the more ancient authorities gives a very different sense.
(*' What is the difference in the use of the dative and accusative of time, as in Acts 13:2020And after that he gave unto them judges about the space of four hundred and fifty years, until Samuel the prophet. (Acts 13:20), etc.? ')