See also
The Story So Far
Grail Challenges
The End
It’s 23 days from March 20 to April 12th. The story itself probably covers twenty days.
At least four days for driving.
Being in mystical places should always be three days: three days in the Green Knight’s realm, three days in the Fishers’ (or three days on the tree for Dean), etc.
#March 20: vernal equinox. Joseph Temple dies. Dean dreams of his murder.
#March 21: Driving day.
#March 22: Arrive in Bethlehem, PA. Meet Bethany Fisher and learn about Lorcan Murphy. Break into his house, etc.
#March 23: Castiel tells them more about their mission. In the morning they leave for the north.
#March 24: Find the dish at Mystery Hill. Lorcan finds them at their motel. They leave for the safety of Bobby’s.
#March 25: arrive at Bobby’s. Dean rests.
#March 26: Dean tries to rest and fails. Castiel comes with healing stones.
#March 27: Dean finally starts improving.
#March 28: Dean realizes they need to go to Chicago.
#March 29: Dean recovers.
#March 30: Sam and Bobby return, the boys leave for Chicago (5-hour drive?)
#March 31: Day one of searching.
#April 1: this would be a good day for the Trickster to show up. Maybe he shows them how to find the Green Knight?
#April 2: in the Green Knight’s realm
#April 3: in the Green Knight’s realm
#April 4: driving to Wyoming
#April 5: Palm Sunday; driving to Wyoming
#April 6: Medicine Wheel confrontation
#April 7
#April 8: Passover begins at sundown
#April 9: Full moon
#April 10: Good Friday
#April 11
#April 12: Easter
Then however much time passes between when Dean gives up on waiting for Castiel and when Castiel finally returns. (Summer solstice is June 21, also Father’s day this year.)