Water when the soil/potting mix is dry.
DO NOT keep the mix soaking wet. Push your index finger down into the soil as near to where the roots would be as possible. If when you remove your finger there is any moisture at all, DO NOT water. Also do not allow the soil to dry out completely for too long of a time between waterings>>the water would just run straight through and out the bottom as it would be too dry to absorb much water. Its useful to provide a saucer and after the initial thorough watering, water the plant when needed by adding it to the saucer and allowing it to soak up into the potting mix from below. ALWAYS use a potting MIX with PERLITE to allow drainage and air to the root system. Garden soil or potting soil cakes up and hardens like cement and does not promote good drainage OR allow air to the root system.
IF you are watering an in-ground plant, I'll assume you arent getting much rain in San Diego? IF your soil drains water off fairly quickly, does not retain it for long, and the temps are HOT daily and its DRY, you could pretty much keep a 24 hour drip going onto it without any problems! Realistically, you will have to gauge the amount of time it takes for the soil within a foot or 2 away from the plant (depending on the size of the plant) to completely dry out. Then when you figure that out, water thoroughly and just repeat at the same time cycle. Once it has become established, you may only have to water during times of no rainfall or extended periods of drought.