It rather depends on what you're doing and how you feel. :)
If you're taking any kind of detox compounds, footpads or suffering candida overgrowth or leaky gut, you should enema-tastic near daily.
Once you start equalizing, then just once or twice a week should be all you need. Once you reach your health goals, then you only need to do them post-flush, after really bad cheats, during seasonal allergies, or when there's a flu virus going around.
Any time you're symptomatic, enemas will help you stay within your comfort zone. :)