No assurances needed.

It aint cut and dry.  Each year can and usually is different, depending on the weather.  However, I can tell you that when the water temp hits about 54, maybe 52 (sustained that is) I get excited that the true pre-spawn movement has started (largemouth).  From there you just have to be on the water as much as possible to determine what is happening, meaning everyday get into the shallows and look.  Its that simple.