Even 7 days will help. Later you might be able to go longer.

I recently did a seven day cleanse. It was great. It was my first time doing a cleanse and I absolutely felt and looked fabulous. My skin actually had a glow, and my hair so lustrous! I recommend it. I plan to do a ten day'er next month! Good luck!
PS( First two days were a little rough, though...caffeine withdrawals and expelling toxins!)

7 days will still be helpfull. Be sure to try and end on an *up*. Meaning if you're in a detox keep going until it's out & you feel better. If you feel great the whole way through then you're set. Happy cleansing! :)