2 days beforehand is your best bet, but they're truly at their best right after preparation. Some homemade cake pops benefit from chilling for a day or so, letting the frosting sort of seep into the cake to make them more moist. But since our Halloween cake balls are actually made with donut holes, they're tastiest served right away. So, any longer than a day or two in advance is a no-go! They’ll be mushy, messy, and not at all the cute Halloween treat we’re going for.