When do the events of GTA Online take place in the timeline?

In the early days of GTA Online, it seemed pretty evident that the occurrences in the game were a prelude to the events of the Story Mode. Characters from the Story Mode like Lester and Lamar would appear in the game, and their interaction with the protagonist signaled that the events of Story Mode hadn't yet taken place.

However, players would soon start picking up on character dialogues that would refer to the events of Story Mode. This is where GTA Online's timeline started to get a little hazy, and players were no longer sure whether this was a prequel or now a continuation of the Story Mode timeline.

In the most recent GTA Online update, the player is tasked with recovering a sensitive document that is important to the Madrazo Family. At the end of the Cayo Perico Heist, players discover that the files were actually intimate pictures of Trevor and Patricia Madrazo, which is tied to the events of the Story Mode.

When do the events of GTA Online take place in the timeline?

Considering the recent developments, it is safe to assume that GTA Online has moved way past the events of the Story Mode and is building an entirely new timeline of its own.

Given that Trevor began to set up his narcotics operation shortly after the "Series A Funding" Heist, it can be gathered that GTA Online was still a prequel at that point.

However, shortly afterward, characters like Tao Cheng began to appear in Online, all while dropping hints to the events of Story Mode. The biggest hint came by the way of Agent 14, who proclaimed that the year is 2017, 4 years after the game was initially set.

This means that the events of GTA 5's Story Mode happened sometime between the Series A Funding Heist and The Doomsday Heist in 2017. Therefore, after the original 5 Heists in GTA Online, the game caught up to the Story Mode timeline and has steadily progressed past it.

As it stands, the Cayo Perico Heist takes place in 2020, and the events of the Story Mode are 7 years old, like in real life. GTAbase provides a great breakdown of the timeline of GTA Online, complete with dates and coinciding events.