1997 (Y17) AD = 116 MM = 72 TR = 71 RH = 69 M = 39 BW = 27 CW = 25 PW = 21 FGW = 19 HG = 18 H&R = 17 GW = 16
[Harry]'s third lesson with [Dumbledore][Harry] and [Dumbledore] together watch the memory of [Tom Riddle] returning to the [Gaunt house] and a fuzzy memory of [Riddle] asking [Professor Slughorn] about [Horcruxes].
This happened the first day back from the Christmas holidays, and a "few days after New Year." On the [HBP] calendar, this is Monday, January 6.
[Ron]'s seventeenth birthdayShortly after waking up, [Ron] accidentally has some of [Romilda Vane]'s [love potion] - and after [Slughorn] provides him with an antidote, he inadvertently poisons [Ron] as well. Fortunately, [Harry] reacts quickly and gives [Ron] a [bezoar], saving his life.
[Harry]'s fourth lesson with [Dumbledore][Harry] arrives at his lesson with [Dumbledore] having forgotten to do his homework and get the full memory from [Slughorn]. They watch several memories, including [Voldemort]'s applying to teach [Defence Against the Dark Arts], and [Dumbledore] warns [Harry] that further lessons will be useless without the memory from [Slughorn].
[Horace Slughorn] finally gives up his memory to [Harry] - thanks to [Felix Felicis] ([HBP22])He races to [Dumbledore]'s study at midnight and together they watch the full memory, discussing [Voldemort], [Horcruxes], and the [prophecy] - along with how [Harry] is going to react to all three ([HBP23]).
We know this happens on April 21 because [Apparition] tests were the same day, and the sign posted in the [Gryffindor common room] in [HBP21] specified the date. This works well with our calendar, too; the 21st is a Monday, we already know from [HBP9] that [Harry] has [Potions] on Mondays, and most of his lessons with [Dumbledore] have happened on Mondays as well.
[Harry] uses the [Sectumsempra] curse on [Malfoy][Snape] quickly arrives to heal [Malfoy], but [Harry] lands in [detention] every Saturday for the rest of the year.
[Harry] serves his first [detention] with [Snape]; meanwhile, [Gryffindor] wins the [Quidditch Cup][Harry] returns to [Gryffindor Tower] after his [detention] to find a massive celebration - and immediately kisses [Ginny] in front of everybody.
[Harry] and [Dumbledore] retrieve the fake [Horcrux] from inside [Voldemort]'s sea [cave]We are given no indication of the date, except that it's June.
The Battle of The TowerWhile [Dumbledore] is away, a gang of [Death Eaters], led by [Draco Malfoy], sneaks into [Hogwarts] through the [vanishing cabinet] in the [Room of Requirement]. They battle the [Order of the Phoenix], and when [Dumbledore] and [Harry] return, Dumbledore freezes Harry and [Draco] arrives to [Disarm] [Dumbledore] ([HBP27]).
After a standoff, [Snape] arrives and kills [Dumbledore], and the [Death Eaters] flee the school. [Harry] then discovers that the [locket] is not the real [Horcrux], but rather that it was replaced by a fake one from [R.A.B.] ([HBP28]).
[McGonagall], now acting as headmaster, meets with the [Order] and with the [heads of houses], determining that students will be allowed to stay for [Dumbledore]\'s funeral ([HBP29]).
[Dumbledore]'s funeralMuch of the British Wizarding World comes to [Hogwarts] to bid farewell to the "greatest headmaster [Hogwarts] ever had."
After rejecting [Scrimgeour] again and breaking ties with [Ginny], [Harry] walks off with [Ron] and [Hermione]. He pledges to find the [Horcruxes] himself, and they pledge to stand with him the whole time.
[Harry Potter and the Philosopher's Stone] is publishedIt is published only in [Britain] until the following year.
Battle of the Seven Potters
The [Order of the Phoenix] attempts to release Harry from [Privet Drive] only to be ambushed by [Death Eaters]. An aerial battle ensues which ranges over the southern counties of England between [Little Whinging] and the [Burrow].
[Fleur Delacour] and [Bill Weasley] get married. The reception is broken up by a [Death Eater] attack.
Story of the Locket Revealed
New Hogwarts Headmaster
With Death Eaters in control of the Ministry, Severus Snape becomes headmaster of Hogwarts.
The Infiltration of the Ministry
Harry, Ron, and Hermione use Polyjuice Potion to impersonate Ministry Employees. They recover a Horcrux and make a narrow escape.
1998 (Y18) AD = 117 MM = 73 TR = 72 RH = 70 M = 40 BW = 28 CW = 26 PW = 22 FGW = 20 HG = 19 H&R = 18 GW = 17
[Harry Potter and the Chamber of Secrets] is publishedIt will not be released in the [U.S.] until the following year.
[Jo Rowling] publishes the first [Daily Prophet newsletter] for members of her fan club
[Harry Potter and the Sorcerer's Stone] is published in the [U.S.]