The following contains possible spoilers for classic and modern episodes of Doctor Who.
Where does the Mondasian colony ship from TV: World Enough and Time play into what we know about the timeline of Mondas?
The following is what I have gathered, please let me know if any of it is incorrect or if there is more to be added. This is also specific to the Mondasian timeline. Cybermen originating from other independent sources (like Pete's World and Marinus) are not included.
It's 1986 on Earth when the "original" Mondasian Cybermen attempt to steal the life-force of Earth to replenish Mondas. Since Mondas had drifted to the edge of space, the Mondasians started "upgrading" themselves to survive. At this point the Mondasians have all been converted to Cybermen and have technology advanced enough to pilot Mondas ~200 light-years next to Earth (AUDIO: The Silver Turk). These Cybermen were thwarted by the First Doctor and Mondas was destroyed. (TV: The Tenth Planet)
After Mondas was destroyed, it seems some the surviving Cybermen split up, some sticking around Earth while others traveled to Telos and Lonsis (AUDIO: Human Resources). The Cybermen on Earth presumably hid in the London Sewers while they hatched a plan in the late 1900s ('87-'99) to paralyze the Earth with a hypnotic signal, boosted by their ship on the dark side of the Moon. Their ship is ultimately destroyed by a Russian rocket, thanks to the Second Doctor (TV: The Invasion).
In 1988 the Seventh Doctor prevents the Cyber-Leader's plans of converting Earth into "New Mondas" (TV: Silver Nemesis). Unknown what point in time/path these Mondasian Cybermen are from.
It's 2070 on Earth and the Cybermen are still weak. They plan an attack on Earth's Moonbase to rebuild their numbers (TV: The Moonbase). Around the same time (2079), they invade Earth's Space Station W3 to use it as "a becaon for their invasion fleet" and are both times thwarted by the Second Doctor (TV: The Wheel in Space). The Cybermen fell back to Planet 14, using it as a base (PROSE: Killing Ground).
After Mondas was destroyed, some surviving Cybermen traveled to Telos and killed most of the native Cyrons. The Cryons required sub-zero temperatures to survive and lived in underground refrigerated cities which the Cybermen took over to cryogenically freeze themselves. It's the 2400s (400-500 Earth-years after Mondas is destroyed), and there's an attempt to revive the Cybermen by an archaeological expedition from Earth. The Second Doctor destroys the Cyber-Controller and reseals their "tombs" (TV: The Tomb of the Cybermen).
It's somewhere around 2495-2530 and the Cybermen from Telos are awakening from their tombs. They have a new/rebuilt Cyber-Controller and have taken a timeship that landed on Telos. They travel back to 1985, one year before Mondas is destroyed, and attempt to prevent its destruction. They park another ship on the dark side of the Moon and plan to redirect Halley's Comet into Earth, destroying it before Mondas absorbs a critical amount of energy. This time it's the Sixth Doctor facing against the Cyber-Controller whom he thought he had destroyed in his Second incarnation, seemingly destroying him for good (TV: Attack of the Cybermen).
Where does the Mondasian colony ship come into play? As far as I know, Mondas wasn't only Earth's twin, but they also evolved around the same time, in the same solar system, and in the same orbit (TV: The Tenth Planet). When the Moon formed, it knocked Mondas out of orbit (AUDIO: Spare Parts).
Since the colony ship was built for Mondasians, it must be before Mondas converted itself into Cybermen, which they only did because they were floating in the vastness of space. It seems if they had a colony ship, they could board that and leave Mondas behind, no upgrades required. This leads me to believe it was before Mondas was thrown from orbit, but that back was when the Moon was formed and Humans nor Mondasians didn't have the technological capability to build such a ship.
This would place the creation of the Mondasian colony ship between of the formation of the Moon and 1986. This seems seems very unlikely considering Earth's progress at that time. Significant jumps in technology didn't occur until after the Mondasians were cyber-converted. When the cyber-conversions started, they had underground cities roughly equivalent to England in the 1950s (AUDIO: Spare Parts) which means Mondasians could not have built the colony ship before they were cyber-converted.
This leads me to ask, did any native Mondasians survive the cyber-conversions and the destruction of Mondas? We know there were two Cyber factions, the Mondans and the Faction, the latter colonizing Planet 14 and the former piloting Mondas to Earth (PROSE: Iceberg). Perhaps non-converted Mondasians were able to travel somewhere, creating the colony ship in their far future?
The colony ship came from Mondas, meaning it was built there and leaving to pick up colonists. It left with a skeleton crew, including Jorj who I believe he was the only non-Mondasian (TV: World Enough and Time).
(Rhetorical questions:) Was the ship built by the Cybermen to gather more people to upgrade in an attempt to replenish the energy of the planet (placing this before the events of TV: The Tenth Planet, only to have it never return? Did a few Cybermen come along to jump start the conversion factories? Where did the non-cyber crew come from, did they make a pit-stop knowing they needed a human population to convert? Did the Mondasians on board resort to what their ancestors did when Mondas was in the vastness of space and upgrade themselves, or did it evolve independently of Mondas (before/after)?
When was the colony ship constructed?