When did I first come out in support of ngdp targeting?
Damned if I remember.
If you are asking: “Should monetary policy and fiscal policy together aim at a stable growth path for nominal GDP?”, I think the answer is that I have always believed that.
If you are asking: “Should monetary policy drop its inflation target and instead do whatever it takes to maintain a stable growth path for nominal GDP, no matter what that requires it do, no matter what fiscal policy is?”, I think the answer is sometime in 2010—but as something that the Federal Reserve should try, not necessarily something that it can do. Cf: http://delong.typepad.com/sdj/2010/12/scott-sumner-plumps-for-nominal-gdp-targeting-of-a-sort.html