There are respected economists that believe that the economic downturn has bottomed or is in the process of bottoming. This fits the technical definition of a recession end, so their answer might be: now.
This is not to say that the economy is in good shape, or that employment has recovered, or that economic growth has recovered. Those millions of people who have lost homes or jobs will tell you, rightly, that the economy still feels like it is in recession.
Recent economic statistics, though, point to a light at the end of the tunnel, and it is not a train; it is slow but sure economic recovery.