Whenever the soil is dry all the way to the bottom of the pot. There’s no way to tell how often that will be, it depends totally on things like the amount of light, the size of the plant, the kind of soil, the size of the pot, the amount of water used previously. You’ll have better luck with plants if you determine when to water by testing soil moisture rather than paying attention to some given schedule and/or amount.

Marlie Graves's answer to How often should I water my houseplants?