i cant give you an Exact measurement, just water the soil until its submerged under water. Water the soil whenever it feels dry, and u will be fine. Dont give nutrients until three weeks after they have sprouted, give them a recommended feeding with some veg nutrients, i prefer something like 5-1-1, which means it has a high amount of nitrogen, giving the plants a vertical boost. If you want something to boost ur rooting, look into super thrive, or a weak cloning solution to add to your watering. These will increase the abundance of roots.