This interview, in discussing the placement of Age of Ultron, states "it's implied that the events [of Winter Soldier] have happened, and we're a little bit a ways from it. I don't know, maybe a couple months."
Not hard evidence of much, but maybe a sign we should be thinking about pushing AoU back into 2014.
Except AoS showed otherwise. There's no hard evidence (no dialogue, no on screen dates, no props with dates, nothing; not even a year) seen in AoU. Also, the "little bit a ways from it" and "I don't know, maybe a couple months" comments don't instill much confidence (this is what I'm talking about in terms of the producers of the MCU not paying much attention to the timeline... I guarantee that dude just kind of made up the answer, and that it hadn't really been discussed internally regarding an exact timeline or frame of time--it's made intentionally ambiguous in Age of Ultron).
If it's only been a couple months since the events of Winter Soldier, that means Age of Ultron would occur around January, maybe February of 2014. Didn't see any snow on the ground on New York (only in the mountainous regions of Sokovia, actually).
Also, that would make AoS's 2nd Season impossible or incorrect. For one, we know AoS Season 1 ends towards the end of October, 2013. Season 2 picks up some time later, and Coulson mentions they've been chased all winter by Talbot, indicating AoS Season 2 starts sometime after winter, early Spring at the earliest, which wouldn't work with how it crosses over with AoU towards the end of the second season.
It would also require pushing ALL of AoS Season 2, Guardians of the Galaxy (that's definitely occurring in 2014 based on the hard date of 1988 in the opening prologue scene and the "26 years later" tag in the next scene), and Age of Ultron all in January of 2014? It just doesn't work.
You could argue that GotG can be placed after Age of Ultron, but that's not the case because of it being a Phase 2 film and the Avengers films capping off the phases, and the chronology of it is obvious based on the plots of GotG and AoU each centering around a stone (just as Thor-TDW did).
The AoU mid credits scene is a sort of capping off of the fact he knows the location of four of the six stones:
-Tesseract/Space Stone is in Asgard
-Loki's Sceptre/Mind Stone is in Vision's forehead
-Aether/Reality Stone is in The Collector's Museum
-Orb/Power Stone is in possession of the Nova Corps on Xandar
No doubt the last two will be revealed somewhere along the way in Phase 3, and I suspect another will play a role in Doctor Strange and/or GotG2.
I also think that Thor - Ragnarok will end as expected and implied by the name, with Asgard in ruins (perhaps attacked by Surtur or other enemies of Asgard, and manipulated by Thanos into doing so), and Thanos shows up in the mid or post credits scene to obtain the Tesseract.
Infinity War, Part 1 can open with similar attacks when necessary to obtain the other 5 stones (a montage, it doesn't need to be a drawn out series of overly long action sequences).
Have Thanos come to Earth at that point to obtain the last stone he needs (Vision's Mind Stone), and the Avengers, Guardians, and a cosmic entity or two take him on.
Part 2 begins with the actual battle, a quick loss, recuperation/cavalry riding in portion, and final battle and fallout/epilogue/set up for the next chapter (Phase 4).
