Timeline

300 Million B.C.

 * Phineas, Ferb, and Candace arrive in prehistoric Danville. ("It's About Time!")
 * Isabella and The Fireside Girls arrive in Prehistoric Danville and rescue Phineas, Ferb, and Candace. ("It's About Time!")

27,000 B.C

 * Conk is cryogenically frozen in a block of ice in prehistoric Danville.
 * Prehistoric mammals arrive in prehistoric Danville.
 * Phinabunk and Gerb invent the wheel.
 * Can-tok invents fire.

1524

 * Princess Isabella gets rescued by Phineas and Ferb. ("Doof Dynasty")

Victorian age

 * Jekyll Doofenshmirtz is born.
 * Jeremiah is born.
 * Constance is born.
 * Ferbgor is born.
 * Dr. Phineastein is born.
 * Unnamed Isabella lookalike is born.

1800s

 * Pizzazium Infinionite is discovered in 1894. ("Vanessassary Roughness")
 * Xavier Onassis builds a time machine. ("It's About Time!")

1900s

 * In 1903, Baljeet's great grandfather entered a bicycle race but fell into a tiger pit. ("Tour de Ferb")

10s
In 1914, Ohio Flynn and Rhode Island Fletcher find the amulet of Juatchadoon ("Phineas and Ferb and the Temple of Juatchadoon")

20s

 * In 1924, Baljeet's grandfather entered a bicycle race and avoided the tiger pit but not the tiger. ("Tour de Ferb")
 * Mr. Slushy Dawg was founded in 1929.

40s-50s

 * Reginald is born in England.
 * Clyde is born.
 * Betty Jo is born.
 * Lorraine is born.
 * Danny's parents meet and fall in love through "boogie-woogie" music.
 * Dr. Lloyd Wexler is born.
 * Winifred is born.
 * A short movie is made about Pizzazium Infinionite, to celebrate its 50th anniversary in 1944. ("Vanessassary Roughness")
 * In 1952, Professor Ross Eforp tried to create Football X-7, but failed. ("My Fair Goalie")
 * A UFO crash lands in Roswell, New Mexico.
 * In 1957, Baljeet's father entered a bicycle race with a cage around him to outsmart the tiger but he was wrong.("Tour de Ferb")

60s-70s

 * Danny of Love Händel is born.
 * Linda Flynn is born of Clyde Flynn and Betty Jo Flynn.
 * Lawrence Fletcher is born of Reginald and Winifred Fletcher, in England.
 * Doofenshmirtz is born in Gimmelshtump, Drusselstein.
 * All people of Gimmelshtump have to give their lawn gnomes away for money. ("Lawn Gnome Beach Party of Terror")
 * Roger Doofenshmirtz is born.
 * Heinz Doofenshmirtz draws a face on a balloon and calls it Balloony. He loses it, and is not much later found by Mitch. ("The Chronicles of Meap")

80s

 * The reverse engineering craze hits its zenith in 1982 with the band Zanzibar's hit song, "What Do It Do?"
 * Linda and Heinz go on a date.
 * Linda becomes the famous one-hit wonder, Lindana. She goes on "The Fun Tour" in 1985.

90s

 * Love Händel is formed.
 * Doofenshmirtz marries Charlene.
 * Vanessa Doofenshmirtz is born.
 * Candace is born in Danville.
 * Phineas is born in Danville.
 * Ferb is born in England.
 * Isabella is born.
 * Buford is born.
 * Baljeet and Mishti are born in India.
 * Linda and Lawrence fall in love at Love Händel's farewell concert.
 * Love Händel breaks up.
 * Flynn-Fletcher Antiques founded.

2000s

 * Bucky dies and is replaced by Perry.
 * Isabella forms a crush on Phineas.
 * The Phineas and Ferb series starts ("Rollercoaster").
 * Phineas and Ferb construct the Coolest Coaster Ever ("Rollercoaster").
 * Phineas and Ferb make a backyard beach ("Lawn Gnome Beach Party of Terror").
 * Phineas and the Ferb-Tones is formed ("Flop Starz").
 * Phineas and the Ferb-Tones performs for the last time ("Flop Starz").
 * The Swamp Oil 500 race goes on ("The Fast and the Phineas").
 * Love Händel reforms ("Dude, We're Getting the Band Back Together").
 * Professor Destructicon captured and arrested ("One Good Scare Ought to Do It!").
 * Phineas and Ferb decide to do nothing for a day ("The Best Lazy Day Ever").
 * Phineas and Ferb get Goldie and make a backyard underwater animal show ("Backyard Aquarium").
 * Phineas and Ferb spread public awareness for the aglet. Meanwhile, Doofensmirtz's high school recording goes viral ("Tip of the Day").
 * Phineas and Ferb meet Thaddeus and Thor ("Thaddeus and Thor").
 * The Paper Pelican flies in the sky and break Howard Hughes and the Spruce Goose's record ("De Plane! De Plane!").
 * Perry is assigned to a new villain and family, making Phineas and Ferb think Perry is lost ("Oh, There You Are, Perry").
 * Perry gets re-assigned back to Doofenshmirtz and the Flynn-Fletcher family.
 * Phineas, Ferb, Isabella, Candace, Linda and Lawrence get shipwrecked ("Swiss Family Phineas").
 * Phineas and Ferb meet their new extreme fan, Irving ("Hide and Seek").
 * Phineas and Ferb and their friends shrink down ("Hide and Seek").
 * Baljeet tries to impress an old friend from India, Mishti Patel ("That Sinking Feeling").
 * The Baljeatles is formed ("The Baljeatles").
 * Phineas and Ferb get X-Ray glasses, that are a total bust and then they improve their X-ray Glasses ("No More Bunny Business")
 * Phineas and Ferb leave current Danville to go back in time (see the prehistoric section of this timeline ("It's About Time!").
 * Phineas and Ferb leave, and later return, from the future Danville ("Phineas and Ferb's Quantum Boogaloo").
 * The Earth and the rest of the universe grow to a massive size, though no one notices ("Attack of the 50 Foot Sister").
 * Isabella grows a crush on Phineas, Candace with Jeremy, and Ferb with Vanessa.
 * Phineas and Ferb directed the Summer version of the music video "It's On" from "Camp Rock 2: The Final Jam" kicking off Disney Channel's Summer Vacation.
 * Phineas, Ferb, and their friends travel around the world ("Phineas and Ferb Summer Belongs to You!").
 * On July 1st Baljeet saves Bufords life and Buford becomes his slave ("The Bully Code")
 * Phineas nad Ferb make winter in July ("S'winter")
 * Phineas and Ferb attend Clive Addison special effects convention ("Nerds of a Feather").
 * Candace finds out Linda is Lindana ("Ladies and Gentlemen, Meet Max Modem!").
 * Phineas and Ferb discover Perry's double life and they go on an adventure to a parallel universe to thwart a more evil Dr. Doofenshmirtz ("Phineas and Ferb The Movie: Across the 2nd Dimension").
 * Perry has a spy mission go terribly wrong causing him to disappear. ("Where's Perry?")

2020s

 * Candace marries and has 3 kids, Xavier, Fred and Amanda
 * Phineas and Ferb arrive from the past, so Candace tries to bust them again
 * Candace goes back in time to bust them, but ends up allowing Doofenshmirtz to take over the Tri-State Area
 * She goes back in time again to stop herself from busting the boys, reversing the bad future

Unknown

 * The Fireside Girls are founded by Eliza M. Feyersied ("Fireside Girl Jamboree")

1960s

 * Heinz Doofenshmirtz is born in Gimmelshtump
 * Heinz Doofenshmirtz loses Choo-Choo, turning him evil

1990s

 * Candace Flynn is born in Danville
 * Phineas Flynn is born in Danville
 * Ferb Fletcher is born in England
 * Lawrence Fletcher marries Linda Flynn

2000s

 * Phineas and Ferb get Perry from the adoption center
 * Perry goes to fight Doofenshmirtz and is turned into Platyborg
 * Doofenshmirtz takes over the Tri-State Area
 * Candace forms the Resistance to fight Doofenshmirtz
 * Phineas-1, Ferb-1, Perry-1, Candace-1 and Doofenshmirtz-1 arrive from the 1st Dimension
 * Doofenshmirtz tries to take over the 1st Dimension
 * Platyborg's programming is reversed, so he is no longer evil
 * Doofenshmirtz is defeated and the Tri-State Area is returned to normal