Most recent use of each letter noted.
A
April 2020
B
Aug. 2020
C
Aug. 2020
D
May 2020
E
July 2020
F
April 2020, Sept. 2020
G
Aug. 2020
H
May 2020, Sept. 2020
I
July 2020
J
Jan. 2020, Aug. 2020
K
July 2020
L
June 2020
M
Aug. 2020
N
May 2020
O
June 2020
P
Aug. 2020
Q
June 2020
R
Jan. 2020, Sept. 2020
S
July 2020
T
Aug. 2020
U
Feb. 2020
V
Feb. 2020, Aug. 2020
W
March 2020, Sept. 2020
X
July 2020
Y
April 2020, Aug. 2020
Z
May 2020
(As of Sept. 2020 thread, post 104)