What can I expect starting a natural colon cleanse?

Depends. Depends on what you mean by "natural colon cleanse." technically, the colon is cleansing itself all the time, as long as we eat enough fiber to give our stool bulk and insure that toxins are bound and carried out. Some people take various products for colon cleanses. Many of these contain senna or other laxative. I discourage these products unless you are constipated.