Timeline
- : Aunt Marge comes to Dudley's tenth birthday party
- : Harry Potter's 10th birthday
- : Quidditch World Cup 1990
- : The Gryffindor Quidditch team is particularly poor this year (1990-1991)
- : Cho Chang is sorted into Ravenclaw
- : Cormac McLaggen is sorted into Gryffindor
- : Katie Bell is sorted into Gryffindor
- : Magenta Comstock dies
- : Arcturus Black, grandfather of Sirius and Regulus, dies
- : Nymphadora Tonks leaves Hogwarts and starts training as an Auror
- : Slytherin wins both the Quidditch Cup and the House Cup (1991)
- : A very exciting trip to the zoo for Dudley's eleventh birthday
- : Harry's Hogwarts letters begin arriving
- : Harry is moved into Dudley's second bedroom
- : A second letter for Harry arrives in Privet Drive
- : A third day of the mysterious letters for Harry
- : A dozen more letters arrive for Harry
Sources