Watering figs is so dependent on your climate and soil type that I do not have an easy answer for when to water. Just know that the fig is a fruit that does well in hot climates and can handle hot days and dry soil. I would look for signs of stress such as wilted leaves and also dig into the soil to see if it is moist before adding water. In a rainy climate this could mean never adding moisture. In a hot, dry area maybe one inch of water a week.  Keep growing, Marianne Binetti