From the USPS on July 28th:
With this new stamp, the Postal Service continues its tradition of celebrating Kwanzaa. The annual Pan-African holiday, which takes place over seven days from Dec. 26 to Jan. 1, brings family, community and culture together for many African Americans. The stamp design features the face of a woman in profile with her eyes closed. Her contemplative demeanor signifies the ways in which observers of Kwanzaa reflect on the seven founding principles, the Nguzo Saba, and their role in everyday life. A kinara (candleholder) with the seven lit candles (mishumaa saba) sits in front of her. Cool tones evoke a sense of inner peace, and vibrant design elements give the artwork a celebratory feel. Art director Antonio Alcalá designed the stamp with original artwork by Andrea Pippins.
New information will appear below the line, with the latest at the top. Kwanzaa in 2020 begins December 26th and ends January 1, 2021.
Updated December 5th:
The Scott catalogue number for this issue is 5531.
Updated September 16th:
Here are the first-day postmarks for this issue: 
The Digital Color Postmark measures 2.43″ x 1.49″ 
The pictorial postmark measures 1.93″ x 1.23″
Updated September 10th from the Postal Bulletin:
On October 13, 2020, in Nashville, TN, the United States Postal Service® will issue the Kwanzaa stamp (Forever® priced at the First-Class Mail® rate) in one design, in a pressure-sensitive adhesive pane of 20 stamps (Item 574900). The stamp will go on sale nationwide October 13, 2020, and must not be sold or canceled before the first-day-of-issue.
With this new stamp, the Postal Service™ continues its tradition of celebrating Kwanzaa. The annual Pan-African holiday, which takes place over seven days from December 26 to January 1, brings family, community, and culture together for many African Americans. The stamp design features the face of a woman in profile with her eyes closed. Her contemplative demeanor signifies the ways in which observers of Kwanzaa reflect on the seven founding principles, the Nguzo Saba, and their role in everyday life. A kinara (candleholder) with the seven lit candles (mishumaa saba) sits in front of her. Cool tones evoke a sense of inner peace and vibrant design elements give the artwork a celebratory feel. Art director Antonio Alcalá designed the stamp with original artwork by Andrea Pippins.
No automatic distribution.
How to Order the First-Day-of-Issue Postmark:
Customers have 120 days to obtain the first-day-of-issue postmark by mail. They may purchase new stamps at their local Post Office™ or at The Postal Store® website at usps.com/shop. They must affix the stamps to envelopes of their choice, address the envelopes (to themselves or others), and place them in a larger envelope addressed to:
FDOI – Kwanzaa Stamp
USPS Stamp Fulfillment Services
8300 NE Underground Drive, Suite 300
Kansas City, MO 64144-9900
After applying the first-day-of-issue postmark, the Postal Service will return the envelopes through the mail. There is no charge for the postmark up to a quantity of 50. There is a 5-cent charge for each additional postmark over 50. All orders must be postmarked by February 13, 2021.
Technical Specificiatons:
Issue: Kwanzaa Stamp
Item Number: 574900
Denomination & Type of Issue: First-Class Mail Forever
Format: Pane of 20 (1 design)
Series: N/A
Issue Date & City: October 13, 2020, Nashville, TN 37202
Art Director: Antonio Alcalá, Alexandria, VA
Designer: Antonio Alcalá, Alexandria, VA
Artist: Andrea Pippins, Bowie, MD
Modeler: Sandra Lane/Michelle Finn
Manufacturing Process: Offset, Microprint
Printer: Banknote Corporation of America
Press Type: Alprinta 74
Stamps per Pane: 20
Print Quantity: 15,000,000 stamps
Paper Type: Phosphor Tagged Paper, Block Tagged
Adhesive Type: Pressure-sensitive
Processed at: Banknote Corporation of America
Colors: Cyan, Magenta, Yellow, Black
Stamp Orientation: Vertical
Image Area (w x h): 0.77 x 1.05 in/19.558 x 26.67 mm
Overall Size (w x h): 0.91 x 1.19 in/23.114 x 30.226 mm
Full Pane Size (w x h): 5.55 x 5.76 in/140.97 x 146.304 mm
Plate Size: 160 stamps per revolution
Plate Number: “B” followed by four (4) single digits
Marginal Markings:
Front: Plate number in four corners
Back: ©2020 USPS • USPS logo • Two barcodes (574900) • Plate position diagram (8) • Promotional text
Hopefully HQ will let us have a local ceremony at the Museum of African American Art in my hood eight blocks from my home. They love the Ries Chapter there and we have helped at a number of very successful events there over the past few years.
From Post Bull SEP 10 On Sale 13 OCT USPS# 574904 Pn-20 DCP & PIC No Auto-Distrib FDoI City Nashville TN
Drove past the closest post office (with the difficult agent who isn’t exactly friendly, let alone to stamp collecting) to the old half-empty downtown post office that looks decrepit and feels haunted. In the olden days it had the best postique anywhere. (Long closed, but they still try to accommodate collectors as much as the USPS will allow).
The computer would not sell less than a full sheet of this issue, even though it is just a standard 20-stamp sheet. But, the guy working told me after 20-stamp issues have been out awhile the USPS relents and will let him tear the sheet. No set time period, but he swears one fine day the computer lets him.
Hopefully that is for real and not just a folk tale. Just can’t buy a full sheet of everything, so I’ve been skipping issues. Runs counter to how FDC covers think about getting new covers to Kansas City quickly, but I can change if it really works that way now. Just I won’t believe it till I see it.
Wondering if it has worked out that way for any of you.