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.

Victorian age

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

1800s

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

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 it's 50th anniversary in 1944. ("Vanessassary Roughness")
 * A UFO crash lands in Roswell, New Mexico.

60s-70s

 * Danny of Love Händel is born.
 * Linda is born of Clyde and Betty Jo Flynn.
 * Lawrence is born in England.
 * Doofenshmirtz is born in Gimmelschtump, Druelselstein.
 * All people of Gimmelschtumphave to give their lawn gnomes away for money. ("Lawn Gnome Beach Party of Terror")
 * Roger Doofenshmirtz is born.
 * Doofenshmirrtz 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 Dr. Doofenshmirtz go on a date.
 * Linda becomes the famous one-hit wonder, Lindana 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.
 * Linda and Lawrence fell in love at Love Händel's farewell concert.
 * Isabella is born.
 * Buford is born.
 * Baljeet and Mishti are born in India.
 * Love Händel breaks up.

2000s

 * Bucky dies and is replaced by Perry.
 * Perry is purchased by the Flynn-Fletcher family. (Phineas and Ferb)
 * 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 Swampoil 500 race goes on. ("The Fast and the Phineas")
 * Love Händel reforms for one night only. ("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")
 * The Earth and the rest of the Universe grow to a massive size, though no one notices. ("Attack of the 50 Foot Sister")
 * The day when Phineas and Ferb probably got Goldie. ("Backyard Aquarium")
 * Phineas and Ferb spread public awareness for the aglet. ("Tip of the Day")
 * Phineas and Ferb meet Thaddeus and Thor. ("Thaddeus and Thor")
 * The Paper Pelican flys in the sky and break Howard Hughes and the Spruce Goose Record. ("De Plane! De Plane!")
 * Perry gets re-assigned to a new villian and family, making Phineas and Ferb think Perry is lost. ("Oh, There You Are, Perry")
 * Perry is re-assigned back to Dr. 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. ("That Sinking Feeling")
 * The Baljeatles band is formed! ("The Baljeatles")
 * Phineas and Ferb get X-Ray glasses, that are a total bust and then they improve their rip off 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). From It's About Time!
 * Phineas and Ferb return back from the past. (see the prehistoric section of this timeline). Also from It's About Time!
 * Phineas and Ferb leave, and later return, from the future Danville. (Phineas and Ferb's Quantum Boogaloo)
 * Isabella grows a crush on Phineas, Candace with Jeremy, and Ferb with Vanessa. (All episodes)
 * Dr. Heinz Doofenshmirtz almost gets rid of Christmas during Phineas and Ferb Christmas Vacation!.
 * 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.
 * The family go to Hawaii. ("Phineas and Ferb Hawaiian Vacation")
 * Phineas, Ferb, and their friends travel around the world. ("Phineas and Ferb: Summer Belongs To You")
 * Phineas and Ferb discover Perry's double life and they go on an adventure to a paralell universe to thwart a more evil Dr. Doofenshmirtz. ("Phineas and Ferb: Across the Second Dimension in Fabulous 2D")

2020s

 * Candace marries a husband not identified (Possibly Jeremy).
 * Amanda is born.
 * Xavier is born.
 * Fred is born.
 * Isabella marries either Phineas or Ferb.
 * Phineas and Ferb go to the past (present).
 * Phineas and Ferb meet Xavier and Fred
 * 35 year old Candace tries to bust Phineas and Ferb.
 * 15 year old Candace "busts" Phineas and Ferb in the future, however, nothing comes of it.

Alternative 2020s

 * Candace (alternate) finds the real Candace.
 * Carl becomes an adult
 * Doofenshmirtz (alternate) is the new emperor of Danville

Unknown

 * The Fireside girls are found by Eliza M. Feyerside