This salad tastes best the first day of assembling. The cornbread tends to get a little moist (and sometimes mushy) after being in the fridge for an extended period of time, so I'd recommend serving it the same day as preparing for best results.  It does need to chill in the fridge for about 30 minutes prior to serving to allow the flavors to settle, but this isn't long enough for the cornbread to lose it's shape or sturdiness.