We have three definitive markers. Episode 1 occurs at approx may 2014 as evidence by the helicarrier trip coulson just got back from and age of ultron takes place 2015.
Episode 5 occurs before nov 3rd. Election Day.
Episode 19 occurs just before age of ultron (may 2015).
Can't remember why we know aou is May 2015 but it does occur before ant man which firmly begins on July 17 as evidenced by the promos. Ultron attack was "recent" so may makes sense.
The "May, 2015" date is merely reflective of the month it came out. The first Avengers occurred in real time (a few days in May, 2012) based on behind the scenes material that firmly dated the Museum Exhibit that Loki crashed in May, 2015. The second Avengers is only presumed to occur in May, 2015, but its a safe bet beyond just the alignment with the real world date of release for the movie.
I'm not sure how much time passes between the events in Sokovia and Ultron's destruction and the scene at the new Avengers facillity... a couple weeks? A couple months? I'm not sure. They were still retrofitting it, and unless they built it from scratch it could only be a couple weeks or so after Sokovia. If they did build it from scratch I imagine at least a month had to pass... and odds are, with Tony's money and the desire for cutting edge security, it was built from scratch. So, I'm only guessing, but the closing scene of Age of Ultron likely occurs a month or two after Sokovia... and likely a few weeks or a month or two before the events in Ant-Man when Scott and Sam went at it (because while Ant-Man begins on July 17, we know its likely Ant-Man spans weeks or probably well over a month:
His release from prison on July 17, his hiring and working at the Baskin Robbins (if I recall correctly) had to have been a few days at least, possibly even a week or two depending on how lax their HR department is... in all reality it was probably only a few days. I need to watch it again once it comes out on DVD to see if I can't lay out a better outline for it.
Anyway, as to AoS... we can safely assume AoS Season 2 begins in or around May, 2014, and the first five episodes likely run from May into early or mid Summer (June, July if you really push it and stretch it out, but that's unnecessary given the jump between episodes 5 and 6 (thanks again for pointing that out).
We can safely assume the remainder of AoS (episode 2x06 onward) picks up in late 2014 (Fall sometime, but its impossible to determine with any kind of exact or even rough estimate beyond late in the year).
If there are no other mentions of the election after Episode 5 (I can't remember) it may even be possible to just place 2x06 through the end of the season all in 2015, since there aren't any large time jumps in those episodes, with it running from sometime in early 2015 to May.
And that would leave Daredevil in August/September.
AoS 2x01-2x05 in Spring to Summer, 2014.
Daredevil Season 1 in late Summer/early Fall, 2014.
AoS 2x06-2x22 from either late, 2014 or early 2015 throught to May, 2015.