The series of Selichos prayers recited in preparation for the “Days of Awe” of Rosh Hashanah and Yom Kippur begin this Saturday night, after midnight (after the Ashkenazic custom; the Sephardic community begins on the 1st of Elul).
On subsequent days, the custom is to recite the Selichot in the early morning hours, before the morning prayers, each morning up to and including Elul 29, the eve of Rosh Hashanah.
More about Selichos – HERE.
Selichos with the Rebbe
http://www.chabad.org/427556