What are the correct dates for 2023?

I just got it by setting my date back to 2017 and following the dates on the calendar. (This also worked for mother's day which I was struggling on at first until the date switch) Just remember to make sure it saves when you go outside. Good Luck and thanks for the guide.

Whenever I play Arkham City on Steam, the Sionis Industries calendar doesn't have circled dates, but when I go to a specific holiday -by waiting patiently- the month still gets scribbled out after talking to Calendar Man.

Is this a glitch, or do I need to adjust the settings of my game? And if yes, what settings will work?

use the 2012 calender

if you're like me and plan on changing the date on your computer to get this achievement, it turns out it has to be a date that has already occurred. I was trying to do the dates of the holidays in 2022, but when I got Mother's Day (which hasn't happened yet as of writing this) he wouldn't talk to me. I would, for simplicity's sake, just do all the dates as they would be in the previous year.

Im probably digging a dead Guide, yet some of the dates are incorrect.
The correct dates is:

-January 1st, New Years Day
-February 14th, Valentines Day
-March 17th, St. Patricks Day
-April 1st, April Fools Day
-May 9th, Mother's Day* (not 8th)
-June 20th, Father's Day* (not 19th)
-July 4th, Independence Day
-August 16th, St. Roch's Day
-September 6th, Labor Day* (not 5th)
-October 31st, Halloween
-November 25th, Thanksgiving* (not 24th)
-December 25th, Christmas (not 28th)

can u change dates on your pc? will that work?

As others said it's better to look at the calendar next to his cell. Lot of these dates doesn't fit.

thanks dude ;)

I don't know if anyone noticed, but there is a chart next to his cell with each of these dates circled. It might help you go through this faster if you don't want to tab over to steam to check each date.