Core 2010s culture started in 2011/2012

Yeah I think these years were clearly more 2010s than people give them credit for, in 2011 the song Levels by Avicii sounded absolutely nothing like a song released in the 00s. Gangnam Style was a thing in 2012 as well, that’s one of the most 2010s things I can think of along with the Party Rock Anthem.

Yeah, 2010 had a lot of 00s holdovers musically, 2011 is the first proper 10s year when it comes to music. 

2010 surprises me with how musically 00s it is. More than I remember.

It's in a weird no mans land between 00s culture and 10s culture along with the second half of 2009.

CN Real is the embodiment of how 2009 felt. None of those shows have a screamingly 2000s vibe, but it's also not a part of 2010s culture. It's in that weird limbo state.
I think 2010 has that awkward vibe to it as well. By 2011, I'd say we were firmly in the new 2010s culture.

As someone who was in high school in the 2011-12 year, I did notice a shift. That was the year I remember more people started owning Iphones versus Blackberries, Instagram was new and hot, Ipads became commonplace, and Yolo was a popular slang word. 2010 and early 11 while having 2010s traits it still had some late 00s holdovers. 2012 was when the 2010s really started to feel distant from the 2000s. The 2011 shift is underrated. The 2011 shift doesn't get talked about much compared to the 2001 or 1991 shift.

I was thinking of it more, and found further convincing evidence of the core 2010s starting in 2011/2012.
A big one is politics. Now, so many on here like to naively assume that the early 2010s were completely apolitical, and there was no SJW stuff in that era, even myself sometimes. It is true that the early 2010s were generally a calm era where politics and pop culture were separated. However, it can actually be seen how the early 2010s was when internet activism and SJW politics really got its start. In 2011, we had the start of modern-day internet activism with Occupy Wall Street and the Arab Spring. Both of these events spread via the traditional protest of course but there was also the usage of the internet to spread awareness of it. Another key event that really led us into the 2010s era of the internet is SOPA/PIPA. These were government acts that were strongly protested across the internet, with many websites such as Google and Wikipedia blacking out their sites for one day. This also led to the shutdown of prominent filesharing site Megaupload. This showed how the internet was becoming more centralized, but also how government control was becoming more enforced on the internet. 2012 only saw the further build-up of core 2010s culture. Kony 2012 is a prominent one, with the hashtag #Kony2012 spreading like wildfire after the video was posted. However, this is also when SJW culture really got its start. Most notable is the murder of Trayvon Martin, which is what triggered the Black Lives Matter movement. Fourth-wave feminism also became prominent this year. This is when Anita Sarkesian launched a Kickstarter for her controversial series "Tropes vs Women In Video Games", which sparked lots of controversy. This was one of the key events that would eventually lead to the Gamergate controversy, which, along with the Elliott Rodger shootings in Isla Vista, would lead to feminism gaining even more prominence in 2014, with the latter event being what led to the label "incel".
Gaming also changed dramatically in this time, notably with the rise of indie titles. The most noteworthy being Minecraft, which had its official release in November 2011, and, well, to say NOTHING on its influence in terms of both gaming and internet culture. lets plays, mods, songs, animations, games inspired by it, people complaining about it being overexposed, people who built their entire lives on Minecraft, tons of merchandise, I could go on. Lets players too became a major force starting in 2012, with PewDiePie being the most noteworthy example. Games like Amnesia, Slender: The Eight Pages, and Happy Wheels, among many others, all gained heightened attention as a result of people like him. This kind of symbiotic relationship between small game developers and lets players led to a seismic shift in gaming to where an ordinary person could become a major figurehead through entertaining playthroughs of video games, or by creating a video game.
So when do I think core 2010s culture began? Overall, I'd say the 2011-2012 school year, which I also now consider the quintessential early 2010s school year, is when we really entered core 2010s culture, but if I had to limit myself to just one year, I'd say 2011 is where the shift start, and 2012 solidified it. Personally, I'm going with 2012 as the start of core 2010s culture, since this is really when the decade as we know it, with SJWs, Minecraft, lets players, Instagram, superhero movies, among other things, really became a thing.