When do zombies come out?

If you are referring to what time of day they come out to play, socialize, and devour the flesh of the living, then it all depends on the creator of said Zombies. In I am Legend, the zombies could only come out in complete darkness (meaning sunset). UV sunlight burned them to a ashen crisp. George Romerro's however, could come out at any time. This is favored by most creators, further pushing the concept of they don't rest.