The actual vision of Daniel begins with this verse. Verses 2 and 3 should be seen as preparation for the vision but not as a part of the vision itself.

The first month: this does not refer to the month of January, as may be understood in many languages. The first month in the Jewish calendar is Nisan, which corresponds approximately to mid-March to mid-April in our present system. According to some commentators the dating is significant because of the two great celebrations, Passover and Unleavened Bread (Exo 12.1-20), which occurred during this month. These celebrations were associated with Israel’s past deliverance, and Daniel is thinking about future deliverance of his people. This information can be given in a footnote. It is also wise to provide the reader with a complete table of Old Testament calendar systems along with other readers’ helps or as a part of the glossary. Good models for this are provided in New Jerusalem Bible or in the footnote at Exo 12.4 in the New International Version Study Bible, although permission from the copyright holder is required to simply copy such tables.

That is, the Tigris: this is taken by some commentators as a later addition to the text. But since the “great river” in the Old Testament is usually the Euphrates (see, for example, Josh 1.4), this clarification is necessary for translation reasons in any case. The Hebrew name for this river is Hiddekel (as in King James Version here and at Gen 2.14), but most versions adopt the better known Persian name “Tigris.”

Quoted with permission from Péter-Contesse, René & Ellington, John. A Handbook on Daniel. (UBS Helps for Translators). New York: UBS, 1994. For this and other handbooks for translators see here .