First off, I’ll say that that the Six Sigma Black Belt certification is well worth it. I have the Green Belt, I can say that it has surely stood out when my resume is reviewed by hiring managers who have an interest in Quality or manufacturing.
For me, the preparation was on the job. I was already functioning in an operations environment and the requirement was that within the first year of employment at the company, you need to have achieved your certification.
I was mentored under a Black Belt who has made some serious cost savings to the company with his certification and is recognized for those efforts. The way I see it, take the experiential learning first and that would be a gauge of how well you think you are in line to function in that capacity or how long you need to prepare for the exam.
I agree 100% with John. I went through Green belt training while my boss at the time was going through her Black Belt training through ASQ last year. She commented many times that the way she was taught was very specific and that she needed to use the study material from their curriculum or she would have not been as successful. I know she was able to get our company to buy it so I would recommend trying to get it through your work or see if the university has it available. I was able to find the Green belt material through the shared services page (a little late but still very cool to see it was available).