First of all, just to be clear, there is no such thing as “CMMI 3 level certification.” An organization is appraised to the CMMI using the SCAMPI A appraisal method to determine either the organization’s Maturity Level or the Capability Level of the organization’s processes. The result of the SCAMPI A is not a certification, but simply a rating of the current Maturity Level or Capability Level.

Has your company already achieved Maturity Level 2? Has your company hired a CMMI consultant? Has your company hired an SEI-authorized SCAMPI Lead Appraiser? Has an SEI-authorized instructor provided the SEI Introduction to CMMI class to your company?
If the answer to all of these questions is NO, then hire a CMMI consultant and a Lead Appraiser. The Lead Appraiser cannot provide the CMMI consulting. Most Lead Appraisers are also authorized CMMI instructors, so the next step is to train your process group and any people who might be an appraisal team member on the CMMI.

Perform a Class C appraisal (gap analysis) to identify where you need to focus your CMMI implementation efforts. Use the findings from the Class C to write a process improvement plan, and use the plan to monitor and control your CMMI implementation efforts.

Implement CMMI Maturity Level 2 FIRST. Once you have established the firm project management foundation of Maturity Level 2, and then consider implementing Maturity Level 3. If you try to implement both Maturity Level 2 and Maturity Level 3 at the same time, you will encounter difficulties. There is a huge difference between managing projects at Maturity Level 2 and managing projects at Maturity Level 3.

Once you feel comfortable that you have addressed all of the findings from the Class C and you have had several project cycles to institutionalize the documented processes, then consult with your Lead Appraiser to determine if your organization is ready to conduct benchmarking SCAMPI A appraisal.

There will be more training (appraisal team and PIIDs) and activities leading up to the SCAMPI A, but your Lead Appraiser will tell you exactly what you will need to do to prepare for the appraisal.