Unsung Glory Timeline

Tom Riddle is Born
12-31-1926

Lord Voldemort rises to power
1970

The Marauders start Hogwarts.
James Potter, Sirius Black, Remus Lupin, and Peter Pettigrew all start their first year at Hogwarts and get sorted into Gryffindor.
September 1st
1971

Remus Lupin's friends discover he is a werewolf, explaining his monthly disappearances.
James Potter, Sirius Black, and Peter Pettigrew then resolve to learn how to become Animagi to help Remus out, though it will be several years until they master the magic required. 
November 29th
1971

The Marauders finally learn the complex spells necessary to become Animagi
Sirius Black, James Potter, and Peter Pettigrew then begin to accompany Remus Lupin when he transforms into a werewolf.
1974   Unable to deal with the rising threat of Voldemort, Minister for Magic Eugenia Jenkins is forced from office.
1975

Remus Lupin becomes a Prefect
September 1st
1975

The Marauder's Map is written
Sirius Black, Remus Lupin, Peter Pettigrew, and James Potter explore the castle and grounds in their Animagus forms and learn more about the secrets of the place than anyone, even Filch. They then create the Marauder’s Map, signing it with their nicknames: Moony (Lupin), Wormtail (Pettigrew), Padfoot (Sirius), and Prongs
circa
1976

Sirius gets his own place and joins the Death Eaters to help his brother. This is when the Dark Lord starts taking him under his wing and manipulating him. October
1977

Regulus tries to leave the Death Eaters
1979

Lily Evans and James Potter are married
1979   Regulus Black dies in the sea cave
In 1979, Voldemort demanded the use of a house-elf, and Regulus sent Kreacher, a family elf that he was very fond of. However, the elf was left behind to die by Voldemort on the secret island in the sea cave where he’d hidden the locket Horcrux.
circa 1979

The Death Eaters start to take control over the Ministry of Magic.
1980

Lucius Malfoy goes to Azkaban for reasons known only by Sirius Black
1980

Harry Potter is born
July 31st 1981

The Fidelius Charm is cast to hide the Potters, with Peter Pettigrew acting as Secret Keeper Dumbledore had offered to be secret keeper, but James and Lily had refused, planning to go with Sirius Black instead – but switching to Pettigrew at the last minute at Sirius Black’s behest unknowing that it was all a rouse to gain more information and that their dear friend was betraying them.  
October 31st

1981

Marlene McKinnon is murdered by Sirius Black by command of Lord Voldemort.
1981

Voldemort names Sirius his second in command
1981

Defeat of Voldemort; James and Lily Potter are killed
Voldemort attempts to kill Harry Potter after murdering his parents, but the spell rebounds onto Voldemort. Harry is left alive with a scar on his forehead that hides an accidental Horcrux made of Voldemort’s shattered soul. Voldemort, nearly dead and instead finds himself in a coma.
October 31st 1981

Sirius takes Harry Potter in and raises him in Malfoy Manor.
October 31st

The Death Eaters take complete control over the Ministry of Magic while under Sirius Black’s command. January
1982

The Ministry of Magic begins changing the laws regarding blood purity and rights for those with impure blood.
1982

Lord Voldemort wakes up from his coma 1990-1991

Harry Potter begins his first year at Hogwarts
1991

Dumbledore is killed by Bellatrix Lestrange
Summer of 1992  

Sirius Black becomes Headmaster at Hogwarts. 1992

Remus is hired by Sirius Black to be the DADA professor despite his blood status to keep an eye on him. 1992-1993

Rubeus Hagrid was murdered by young Death Eaters the first week being back to school the 6th year.

George and Fred Weasley were murdered by a Death Eater Orchestrated explosion of their joke shop on 10/31/1996. 

Everything that happened in the books regarding the Trio Era and their schooling did not happen. Harry, Ron, and Hermione were never a trio of friends. This is what gives you the chance to make your character really your own.