Timeline

July 12, 2186 – Reaper War ends with the departing of the Reapers and Shepard assumed to be KIA. While no one knows what really happened , plenty of rumors and speculations exist.
July 15, 2186 – The Great Rebuild begins, starting with the Citadel and the Capitol planets (Earth, Palaven, Thessia, Rannoch, Tuchanka, Sur’Kesh)
January 18, 2187 – Rannoch is the first planet to report that they have rebuilt to functionality (but not full restoration). After hearing this, requests flood in from the other capitol planets for squads of Geth units to help them. The Quarians agree to send 300 Geth to each planet, and 500 to the Citadel.
February 25, 2187 – The Citadel reports restoration, with entirely new representatives (Galyrus Demnos-Turian, Faenia T’Sasia-Asari, and Saldri Tolra-Salarian). The new Council’s first act upon reconvening is The Galactic Unity Act, as well as the recruitment of new Spectres.
‘April 9, 2187 – The Quarian and Krogan embassies on the Citadel are completed. Quarian Admiral Shala’Raan vas Tombay is chosen to be the Quarian Representative, and Urdnot Wrex is chosen to represent the newly reunited Krogan. Raan accepts without hesitation, Wrex accepts as well, but he notifies the council that he’ll be going back and forth between The Citadel and Tuchanka.
July 14, 2187 – The first post-Genophage Krogan is born of Eve and Wrex. They have agreed to name him Urdnot Solus, after the Salarian scientist Mordin Solus who developed and administered The Cure with the help of Commander Shepard.
July 18-21, 2187 – Palaven, Thessia, and Sur’Kesh report functional status, while races such as the Krogan and Batarians report that they’ve never stopped being ‘functional’. Drell, Hanar, and Elcor have also shown signs of significant improvement.
August 3, 2187 – Quarians and Geth work together to develop synthetic nanobots that help improve the reproduction of vegetation. Once the Krogan catch wind of this, a deal is made to have Krogan access to these nanobots in exchange for a small Krogan vanguard.
October 17, 2187 – The Geth begin colonization of Dwarf planets Uriyah and Etiel. When asked why, one unit stated, “It is not that we wish to abandon the creators, we simply desire a place to call our own now that we are being considered an equal to the organic races.”

Timeline

Mass Effect: Rebuilt and Reborn HannShotFirst