Start Point for Improvement Programme in multi-stage process across several business units

We are about to launch a series of transformation events using Lean-Sigma. The end-to-end process covers 8 major sub-processes and these cross three major business units with three General Managers. Additionally, there are a number of suppliers into the process and a distribution company that we sub-contract for the delivery and collection of product into and out of the process.

Does anyone have any thoughts and recommendqations on which part of the process we should start with?

Thanks

David Baker
Lean-Sigma Black Belt