Yes - 2012 in practice. To make the question precise, it clarifies that it refers to the term. It would also be interesting to know when people first head of EA avant la lettre - this could mean many things, but hearing of an EA org certainly counts. For my part I heard of GWWC in 2010, from Pablo Stafforini (benthamite here). I read Peter Unger's book Living High and Letting Die in about 2002, which argues for giving large amounts to effective charities, and is perhaps the first mention of Earning to Give.

[Thread for making and discussing predictions]

To expand on my predictions, I think that global poverty will be the most popular cause except among those who say they heard of EA through LessWrong (whose numbers I'll be interested to see). I also think that skepticism/atheism will be the other social movement with which most identify, and atheism the most popular religious position. In the link Jacy Anthis has given a full set of predictions to test his accuracy.

The question "When did you first hear the term 'effective altruism'?" is tricky because that term was only invented in late 2011, after many of us had heard about effective altruism itself.