Wednesday Kislev 23 5703
Chumash: Vayeishev, Revi'i with Rashi.
Tehillim: 108-112
Tanya: Since the said...the said Likutei Amarim. (p.xvi).
From my grandfather's talks of Elul 5635 (1875):
The three days before Shabbat are a preparation for Shabbat. The Zohar says [1] about Shabbat that "from it are all days blessed."[2]
"All days" refers to the six days of the week on which G-d conferred a general blessing - "G-d will bless you in all you do."
The blessing of Shabbat is for the days preceding it and the days following it. The preparations for Shabbat begin Wednesday, and are announced by the brief L'chu N'ran'na [3] of three verses.
Notes:
Zohar II, 63b, 88a.
Devarim 15:18.
Siddur (Tehilat HaShem) p. 78. First three verses of Psalm 95 appended to Wednesday's Psalm 94. The same three verses begin the Friday night prayers inaugurating Shabbat (Siddur Tehilat HaShem (Kehot) P. 128).