around 4-5 hrs pump once. I stopped 埋身餵 when bb was 3 weeks old and started to pump out the milk & use bottle to feed my bb. In order to have more milk, you need to fix the time to pump regularly (i.e every 4-5 hrs) including mid-night. I have been doing so and it works for me. Once your body get used to pump regularly and every time you 泵清, then your body will produce more milk just like breast feed.