This is my official timeline from my own notes to help my readers keep track of the events, so it WILL contain spoilers. And in case you are wondereing, ADG and BDG stand for After- or Before the Death of Galbatorix, while BA and AA stand for Before Alliance or After Alliance.
Timeline
21 BDG(winter)/ 369 BA(winter) – Mercury is born in our world to a different name
18 BDG/ 366 BA – Mercury's parents commit suicide by drinking quicksilver and try, but fail, to do the same to Mercury
3 BDG/ 351 BA – Mercury changes his last name to Iridium
1 BDG/ 349 BA – Mercury is brought to Alagaësia
0/ 348 BA – Galbatorix dies
1 ADG/ 347 BA – Eragon and Arya depart for the east
2 ADG/ 346 BA – The Disaster of Bullridge happens
11 ADG/ 337 BA – Mercury meets Elva again
20 ADG/ 328 BA – Mercury and Elva become romantically involved
32 ADG/ 316 BA – Mercury orders Elva's death, initiating the Decade of Bloody River
51 ADG/ 297 BA – Arya gives birth to Evandar
74 ADG/ 274 BA – Mercury purges Ilirea and kills Elva, and Arya gives birth to Loivissa
79 ADG/ 269 BA – Mercury gets his memory wiped
86 ADG/ 262 BA – Mercury acquires the deed to Eregion
120 ADG/ 228 BA – Mercury finishes construction of Nolondil
151 ADG/ 197 BA – First sighting of the shade
162 ADG/ 186 BA – Nolondil is chosen as a safe haven
170 ADG/ 178 BA – Nolondil is sacked
171 ADG/ 177 BA – The shade is killed and Mercury departs Alagaësia
226 ADG/ 122 BA – Mercury finds the then 5-year-old Naina Uluth(brightening moon)
237 ADG/ 111 BA – Celiste gives birth to Helen
239 ADG/ 109 BA – The ra'zac empire invades Alagaësia
246 ADG(late spring)/ 102 BA(late spring) – It is decided by the leaders of Alagaësia to have Loivissa try and have Mercury return to the war.
247 ADG(early summer)/ 101 BA(early summer) – Celiste is killed while on her way from Ilirea to Dras Leona to heal the sick and wounded
247 ADG(late summer)/ 101 BA(late summer) – Mercury returns to Alagaësia and ends the 2nd Ra'zac War
248 ADG(late winter)/ 100 BA(late winter) – Mercury is crowned king of the new kingdom of Damocles
248 ADG(early summer)/ 100 BA(early summer) – The Ra'zac Empire is finally defeated at the battle of Rushno, Kilgharrah dies and Loivissa is banished from Damocles by Mercury
306 ADG/ 42 BA – Project Faust reaches its conclusion
348 ADG(early summer)/ 0(early summer) – The Silver Wave Alliance is formed on the 100th anniversary of the Ra'zac Empire's defeat
618 ADG/ 270 AA – Atanalcar's story begins
619 ADG/ 271 AA – Elladan's story begins
641 ADG(spring)/ 293 AA – Mercury begins his invasion of Alagaësia and the dragon rider city of Estildirin
641 ADG(early summer)/ 293 AA – Mercury crushes the combined Alagaësian grand army and subsequently conquers all of Alagaësia
641 ADG(late summer)/ 293 AA – Aiedail is formed with the sole purpose of killing Mercury
642 ADG(spring)/ 294 AA – Mercury ratifies Special Order 66, thereby banishing the existence of eldunarya.
645 ADG/ 297 AA(early spring) – Mercury's body is destroyed and his soul bound to the earth
745 ADG/ 397 AA – Loivissa commits suicide
