How many days after flu onset would bacterial pneumonia begin?

At risk: Once the inner lining of the lung is infected, it is prone to a secondary infection. It may take weeks to recover from influenza, and a secondary pneumonia can occur at any time during that period. There is evidence that the risk for a pneumococcal pneumonia occurs even one week after influenza infection. An interesting link for more information: http://www.cidrap.umn.edu/news-perspective/2013/06