I have been using Chinese herb all my life, usually I go to Chinatown, buy the herb/s, go home and prepare it by myself.
I assume the Chinese herbs you got from sensible.com are in a prepared form for convenience. Don't worry, they should work. Actually, for me, I spent almost 2 months on the Chinese herb (GCG and other bitter herbs) before I start doing the flush because I was afraid of my stones might get stuck when they come out. So in my opinion, you should go through Chinese bitter program before you start the flush. Once you start the flush, you should see the expected results. (If you are lucky, You might also notice some improvement in the process of taking Chinese bitter, especially the GCG herb, generally will work).
I thing I would like to mention is that these Chinese bitter are powerful "de-appetisers", in other words, it is consider Ying-Energy herb and will generally weaken your digestion fire(stomach Yang-Chi) and kidney fi(kidney Yang-Chi), unless you body type is excessive Yang-Energy(have heat, thirst, yellowish urine and tongue coating, etc...). For me, I know after a series of bitter herbs intake, I loose appetite. I hope it doesn't happen to you, but if it does, remember to take some stomach and kidney tonic while you are on Chinese bitter program, such as some honey, ginger soup, rice porridge, chicken stock, etc... They should help.