Water plants until water starts to come from the drain holes,make sure to not leave dry spots in the soil and depending on soil,light,heat,ventilation and plant size.
Water cannot not be scheduled since some plants drink more,heat from the light and fans can dry the soil faster than normal but just having a good mix of soil can
go a long way,like soils with too much perlite will need to be watered every 1-2 days and soil with something like vermiculite in it may retain water a lil longer.
I used to go by the weight of the pot but now i just water when dry on top and repeat the watering process.