2006

David Glasner points out that one could consider Fed "tightening" starting as early as 2006:

... Beckworth and Ponnuru themselves overlook the fact that tightening by the Fed did not begin in the third quarter – or even the second quarter – of 2008. The tightening may have already begun in as early as the middle of 2006.

That's what I said:

The Fed both reduced the monetary base (M0 and MB) and [effectively] raised interest rates (also dependent on MB and M0) starting after 2005 relative to a log linear path of monetary policy from the early 2000s.

Or here:

The Fed was effectively raising interest rates gradually from well before the onset of the financial crisis by having the base grow more slowly than NGDP.