High resolution calendar (July 2011 – March 2012) scan from the Girl’s Generation 2011 Tour brochures. Click image for full size.
Taeyeon (July)
Tiffany (August)
Sunny (September)
Yuri (October)
Yoona (November)
Seohyun (December)
Jessica (January 2012)
Sooyoung (February)
Hyoyeon (March)
Credit: Daveetron