p&b shakes

I am a little new to cleansing and just have a couple of questions about pb shakes.
Is it ok to use an herbal detox supplement at the same time (ie: a boxed system found in a health food store)? Will it keep me in the bathroom a lot (it can't conflict with my work schedule..lol)? Other than drinking lots of water, are there any other really important things I need to know? Oh, and should I wait til this flu-like thing goes away to start a cleanse?

Thanks :)