Nothing else can be done, just check every 6 hours. Very often you will see a grey shadow developing under the shell, that is a sign the duck is working on it. You can usually hear a tapping from inside when you hold it to your ear. You later will see a pip, which looks like a pin is breaking out, or a dimple going outwards. From that point it can still take 24-48 hours until the duck hatches. They are really taking their time, so you will have to sit tight. Try not to open the tub up to often, because the heat and moisture will escape causing a difficult hatch. Name for the duck. Breakout, speedy, rush, champ, oh you will find a name once the personality shines.