It is hard to give an exact time for the initial charging of your Zooka. Zooka batteries are partially charged when they leave the factory, but they may be on store shelves for indeterminate lengths of time. My best advice is to expect to charge the battery for 4 hours or until the LED stops flashing. A full charge should last for at least a week without use, depending on environmental conditions where it is being stored. Temperature extremes will adversely affect battery life.
A fully charged Zooka will play for 8 hours.