(Note that this is still being worked on, and this is basically a heavy adaption of zoogie's "A Pretty Brief History of the 3ds Hacking/Homebrew Scene" from the "3DS hacking scene history" section on GBAtemp)
2011
March
March marks an important date, the release of the Nintendo 3DS in the west, and the creation of 3dbrew.
June
Not sure about info (come back to later)
September
Crown3DS teases a promising video of a flashcard, but instead we got an Engrish website promising the community that they are progressing.
December
Release of tools that convert video to stereographic 3D video that is compatible with the 3DS photo app (maybe paraphrase and look into this more)
2012
Unknown Month
Believed that Neimod's hardware RAM dumps and internal research lead to the first userland and a9 exploits.[1]
March
The first (?) homebrew written in .cxi format, being "Hello World" written by Xcution (auther of CiTRUS,
2013
August
August of 2013 is a pretty important year of the 3DS community, as it is when Gateway-3DS released, being the entirety of homebrew in the early years. At this time, there was basic arm9 homebrew possible via an MSET exploit combined with p3ds, [1] which are python tools for the 3DS.
December
Users in the community figure out how to reverse engineered the Gateway-3DS payload to create their own NAND emulation (or redirecting). Specifically users Smealum and Yellows8 create a private payload called RedNAND.