The duration of the construction period for ITER is ten years, from 2008. The procurement model is such that the ITER Plant Systems will mostly be provided 'in kind' to be integrated into the ITER control infrastructure. In the coming three years, the earliest plant systems will be built and some test facilities will also be required. As a result, the CODAC group (Controls, Data Access & Communications) is already preparing the systems that implement the core functions such as operator interface, alarms handling, communications or data storage, in incremental versions, reduced and tailored for the development and tests of the plant systems before integration. The work is executed in partnership with labs and industries from the ITER parties and has to be organized as a continuous process to match the consecutive integration and commissioning phases of the ITER project. This paper reports on these tasks, including schedules and decisions, with details on two systems named Plant System Host and Mini-CODAC.