Overnight is better. Use a half-round tip shaper to shape the tip. One can be fashioned by tripleing layers of sand paper and shaping it into a 'half-round'. Blacken or darken the sides of the tip. This is an optional step.
Some players prefer to keep the side of the tip natural.
I prefer to blacken Elk tips on pocket billiard cues. This operation is performed using a Sharpie fine point black marker. Be careful not to blacken the ferrule, the only way to remove black effectively from a ferrule is sanding, and you know what that means. My favorite method for blackening a tip is to wet the tip all around the side with the tip of my tongue, then rub the side of the tip vigorously on the felt of the top rail while spinning the cuetip with my hand. This gives the side of the tip a more natural and polished look.