XENOMORPH TIMELINE
Aboard the hijacked colony spacecraft, USCSS Covenant, after the disastrous Prometheus (2012) expedition, the rogue synthetic, David, sends a transmission to the Weyland-Yutani Corporation on Earth, explaining his scientific discoveries after finding the Engineers' homeworld, the strange Planet-4. This transmission explains David's decade of experimentation on Dr Elizabeth Shaw and the destructive black-liquid mutagen, in his quest to continue Sir Peter Weyland's ambitious vision after the events of Alien: Covenant (2017), and the creation of the perfect organism.
David sends a transmission from the Covenant to Weyland-Yutani on Earth, elaborating upon the genetic experimentation he has been conducting on Planet 4.
Advent is a short film released in 2017 that takes place in 2104 in the Alien timeline. In the Alien movies timeline, it comes after She Won't Go Quietly (2104) and before David's Lab: Last Signs of Life (2104).