Do Civil War and Thor Ragnarok happen at the same time?
There's a whole lot of overlapping in the MCU, and often when they refer to timelines (i.e. something happening 9 years ago, or 2 years ago), the math doesn't really add up. However, there is a quote from producer Brad Winterbaum:
“It’s not like, five minutes after Ultron ends we start this movie. It’s a couple years later… This movie takes place basically… You know, it’s hard. In the timeline of the MCU, things kind of happen on top of each other, especially now in Phase Three. They’re not as interlocked as they were in Phase One, you know, during Fury’s Big Week and everything. So [Thor: Ragnarok] happens maybe on top of Civil War, on top of Spider-Man [Homecoming]. Somewhere in that ball park.
Considering at the beginning of Ragnarok he mentions
he'd been searching for infinity stones for the past two years (when talking to Surtur)
And I'd be surprised if Civil War is that long after Ultron (someone may be able to help me with a source here). The actual time of the movie is probably only a week or so, I'd guess that it's probably a little closer to Homecoming than Civil War.
After all, he did live with Darryl for awhile ;)
So it looks like a little over a year between Ultron and Civil War:
In a new interview with Comicbook.com, director Joe Russo said that the amount of time that has passed will be roughly equivalent to how much time has actually passed between movies, meaning Civil War would take place about a year after Age of Ultron.
Add a few months between Civil War and Homecoming, and that comes out to about the correct timeframe. Ragnarok is either during Spider Man Homecoming or shortly afterwards.