The "time switch" is integrated in the power supply unit. I don't know if you can set anything in the current power supply unit, as this was not possible until now. Simply plugged in, pump started and again after 24 hours.

As shown in the first photo, you can set the watering time and frequency. For example, 6 minutes every 4 hours, 6 minutes every 6 hours, 1 or 3 or 6 minutes every 8 hours, 1 or 3 or 6 minutes every 12 hours, etc. There aren't an infinite number of choices, but you can still play around with the number of drips installed in each pot. By the way, the pump makes quite a bit of noise when it's running, which isn't ideal if you're mainly indoors.