There is a statistical distribution for all of these time periods and a lot could depend on things like the infectious dose you received, your immune system's abilities, the particular strain of the virus, how susceptible your cells are to infection with the virus (e.g. do your cells have a high concentration of the receptor the virus is looking for to gain access to your cells?), etc.

I said "Shortly after reaching peak concentration, you begin feeling symptoms", but this is not correct.

Typically peak concentration would hit shortly *after* feeling symptoms rather than before. However, you will be highly infectious a up to several hours before feeling symptoms for influenza.

The high probability zone of being being contagious before symptoms is somewhere around 36-48 hours after exposure for influenza, but someone below mentioned that it could be much shorter for influenza B.

This is just where most people will be contagious. It's possible you would be contagious 24 hours after exposure or not until 72 hours or more.