When the day is signed like This 1, then we need to suppose the day.
When This 2 means confirmed date.
Part I: The Twelve Portals
1. HALLOWEEN
October 30:
First day. Will came to Heatherfield. Suppose it was October 30, because:
October 31:
Next day were HALLOWEEN party.
November 1:
The day after Halloween.
2. THE TWELVE PORTALS
December 4 - Monday:
The girls talks, that THIS started about a month ago. So it must be December. Why 4th?
December 5 - Tuesday:
Yan Lin dies. In Chinese tradition - Funeral should took 3, 5 or 7 days. Suppose December 5 was the day when she died. Lin's started preparing to funeral that tooks 3 days. So next day was:
December 6 - Wednesday:
(second day of preparing, unshown in the Comic)
December 7 - Thusday:
Third day of preparing, and the funeral.
December 8 - Friday:
The day after funeral. The girls are in the school, so it could to be friday.
3. THE DARK DIMENSIONS
December 9 - Saturday:
The Day unshown in the Comic.
December 10 - Sunday:
Will's mom says that it's sunday, so thats how we can suppose previous days.
December 11 - Monday:
Comic begans with text about mondays and math. This is the day when Taranee gots lost.
4. THE POWER OF FIRE
December 12 - Tuesday:
The day after Taranee's lost. In Irma's callendar we can see:
And that's why we can suppose previous days dates, and the year of action! Supposing our theory works: December 10 - sunday was in 1989, 1995, 2000 and 2006.
Let's take look at technology and clothes. I think they are too exclusive for 1989.