Series Timeline

1870's

The events of Fistful of Fruit Juice take place:

Oprah owns a fruit stand in town and works with her friend and business partner Yucks Shmumbers on a way to take fruit juice on the go
Oprah shows Yucks her early version of the Math Room, which she calls "the mathematical figuring out locale"
Yucks invents the first juice box
Oprah leaves the town to deliver newspapers in Norway
After deciding the job wasn't for her, Oprah becomes queen of Portugal
Oprah decides to join Odd Squad and becomes O'Donahue's partner
Yucks takes over running the fruit stand and starts the Shmumbers brand
Big Red invents and starts digging the tube system

The town of Hofferville is inexplicably divided by a giant wall of oatmeal with raisins. Odd Squad agents eventually fix the problem by consuming the wall.

The world argues about the pronunciation of the word "tomato", causing the fruit to fly away. This results in "The Great Tomato Crisis". Eventually, a pronunciation is decided upon and tomatoes return.

1983:
- On March 9th at 2:30, Agent Obfusco thought up the shut off code (123) for the portalnator gadget while apple picking and salsa dancing with six kangaroos (as mentioned in Agent Obfusco)
- Agent Om wreaks havoc at Niagra Falls and is sent to retraining, inciting his revenge plan to eventually shut down Odd Squad as Weird Tom
- The events of Totally Odd Squad take place
  - Agent Oprah becomes Ms. O

1984
- The ballroom overflows and floods headquarters for the first time (as seen in O Vs. the Ballcano)

Agent Oscar joins Odd Squad and becomes a tube operator. He is later fired from the position. He then attempts to be a security guard, but is also fired from that department. (speculation)

Agent Oscar continues to try to find where he belongs at Odd Squad by attempting (and getting fired from) being an Odd Squad lifeguard, concession worker, air conditioner repairman, and kitchen assistant

Agent Oscar gets a job as a door greeter, and is later fired. From there, he attempts working in 53 other positions without success
Agent Oscar gets a job as Ms. O's assistant, and is later fired for the last time
Ms. O creates the gadget inventor position exclusively for Oscar
Oscar becomes an Odd Squad scientist
The Odd Squad gift shop is converted into a lab
The girl working in the former gift shop is given the position and title of Dr. O
Olive, Ophelia, Oakley, and Todd join sometime after this, still in the early part of the decade

January 10th - Beginning of Season 1
December 24th - Olive and Otto help Santa catch his reindeer and deliver presents around the world (as seen in Reindeer Games)
December 31st - Olive inadvertently becomes the countdown crook and finishes everything on her resolution list in order to solve the case (as seen in Party of 5, 4, 3, 2, 1)

May 25th - Odd Todd returns to wreak havoc on the squad
Headquarters floods once again, but this time is saved by Otto and Olive (as seen in O vs. the Ballcano)

January 10th - Olympia and Otis solve their first case.
April 1st - Otis, Oscar, Olympia, and Oona time travel to this day after Oona tosses the Dayinator gadget to Oscar, who misses it. (as seen in Back to the Past)
December 8th - Olympia makes the OddTube video "Pandas"
December 29th - Agent Olo accidentally zaps herself with the Dustballinator gadget and is turned into a ball of dust

January 26th - Agent Olo is turned back into a human again and appears on an episode of Oddtube