It can vary, depending on how dry the air is. Basically, wiggle your finger into the soil or stab a chopstick into it to check the soil/substrate moisture level. Water when the dryness is indicated (organic soil doesn't stick to your finger, substrate is changing to the dry color under the surface, or the chop stick feels dry when you extract it after a few moments).
Obviously watering won't be necessary when it is rainy. It might be occasionally as long as it is overcast. Pay close attention to the soil moisture whenever it is bright and sunny (low relative humidity).