Recent information matters more than old information. The most recent material reflects the studios current plans. Therefore, for example, if there is a conflict between Homecoming and Thor 2, Homecoming wins. If there is a conflict between Civil War and The Avengers, Civil War wins.
The big audience matters more than the small audience. The big audience is watching the films. A smaller audience is watching the television shows. An even smaller audience is buying special editions box sets containing detailed timelines. When there is a conflict between a new movie and an older television series, the new movie wins.
If you need to squint or pause to see the conflict...nobody cares. A lot of people bring up quick flashes of newspapers or blurry calendars in the background as evidence. Although these can cause continuity errors in a technical sense, they do not constitute anything that would bother you unless you were looking for trouble.
With that in mind, here is the new timeline, to the best of my knowledge. It is important to understand that Homecoming is a retcon, and NOT an error. There are three separate references to a span of eight years in the film. If this was an error, it is likely that only one of the three would be inaccurate instead of all three. Additionally, the junior novelization for Homecoming refers to this same timespan being five years. Because novelizations reference early versions of the script, this indicates that the timespan was intentionally changed from five years to eight years later in production. Additionally, five years is accurate to the former timeline. It is extremely unlikely that the studio would alter accurate information in three separate instances accidentally, especially since the three are self-consistent.
Early 2009 - The Incredible Hulk
Spring 2009 - Iron Man
Fall 2009 - Iron Man 2, Thor
Spring 2010 - The Avengers
Winter 2010 - Iron Man 3
2011 - Thor: The Dark World
2013 - The Winter Soldier
2015 - Age of Ultron
Summer 2017 - Civil War
Fall 2017 - Homecoming
I know I brought this up in another thread so I will repeat the following issues:
-Iron Man 2 has the Stark Expo taking place in 2010.
-In the Incredible Hulk, General Ross said that Bruce Banner was on the run for 5 years. This would put the opening credit scenes in 2005 (before Iron Man 1) and the majority of the film in 2010 (alongside Iron Man 2 and Thor).
-In Fury's Big Week novelization, Fury said that it took 2 years for his team to find Captain America's frozen body. They started looking on the same day Tony Stark announced himself as Iron Man in 2009 which will place the ending of CA: The First Avenger in 2011.
-Both Agents of SHIELD and Daredevil TV series established that the battle of New York took place in May 4, 2012 (precisely when the Avengers took place).
-Iron Man 3 begins on New Year's eve 1999 and later, Aldrich Killian said that Tony ditched him 13 years ago. 1999 + 13= December 2012.
-Thor: The Dark World begins immediately following the ending of the Avengers with Loki in chains and answering to Odin for his war crimes on earth. Plus, Darcy said that it's been 2 years since Jane Foster had seen Thor which was in 2010 so this puts the sequel in 2012.
-In Civil War, Zemo said that he spent 1 year plotting his revenge against the Avengers. This tells us how much time had passed since the Sokovia disaster occurred in Age of Ultron thus putting Civil War in 2016.
-WHih News has the bombing in Lagos occurring in May 6, 2016. The U.N. bombing was 1 month later.
-When General Ross stated that the Avengers were operating without oversight for 4 years, he showed footage of all the disasters that happened in the Avengers films, Winter Soldier, and Civil War to prove his point. This would mean that the Avengers first became a group in 2012 and again, placing Civil War in 2016.
AND
-Spider-Man: Homecoming is set 3 months after Civil War.