While this depends solely on the plant you’re watering, this question can easily be answered by checking your water reservoir on a regular basis.
Many self watering containers have a water window where you can monitor water levels without detaching the base, making it easy to see when you’re running low.
After transplant to a self watering container, keep an eye on how fast or slow your plant takes the water. This will give you a more accurate time frame of how often to water.