I don't think there is a "right and wrong" time to handle your snakes. I don't believe that there will be any negative effects when handling one time over another.
I handle my snakes when it is convenient for me. Day, night, evening dawn...when I am awake, and they aren't digesting, if I feel like "playing"...we play. I have not noticed any ill effects because of this treatment, though, granted, I have only had my corn for around 2 months. They still hide whenever they want, and "cruise" whenever they want. They all seem to be very inquisitive and healthy, and none are aggressive, save for the one that was sold to me at a steep discount because of her aggression.
I have yet to find documentation reporting a "consensus" as to when cornsnakes should and shouldn't be handled, except for the 48 digestion requisite.