In this presentation we will discuss the early experience with the CMS computing model from the last large scale challenge activities to the first days of data taking. The current version of the CMS computing model was developed in 2004 with a focus on steady state running. In 2008 a revision of the model was made to concentrate on the unique challenges associated with the commission period. The types of changes needed for commissioning will be presented. In addition we will discuss the challenges in commissioning the major processing workflows for analysis and production and the workflows for data management and data consistency across the distributed computing infrastructure. We will present experiences and results from the final scalability tests of services and techniques. We will also discuss the initial experience with active users and real data from cosmic and collision running. We will address the issues that worked well in addition to identifying areas where future development and refinement is needed.