Check the containers daily. When you water, water thoroughly so that the entire soil ball is moistened.
Water dripping out of the drainage holes is usually a good sign that enough water has been applied.
Light watering does not moisten the entire soil ball. This results in poor root growth and plant performance. Extending the interval between watering is sometimes achieved with the use of one of the many polymers on the market. These are sold under a variety of trade names. They are added to the soil mix and are capable of holding and retaining moisture for use by the plants when the soil is dry.