The Joint European Torus (JET) is the largest tokamak currently in operation in the world. One of the greatest challenges of JET is the integrated commissioning of all its major plant systems. This is driven, partially, by the size and complexity of its operational infrastructure and also by the fact that, being an international environment, it has to address the issues of integrating, commissioning and maintaining plant systems developed by third parties. The ITER tokamak, now in construction, is a fusion device twice the size of JET and, being a joint effort between the European Union, China, India, Japan, South Korea, the Russian Federation and the USA, it will share on a wider scale all of the JET challenges regarding integration and integrated commissioning of very large and complex plant systems. With the scope of leveraging and contributing with some of the history and experience of JET into the ITER project, Fusion for Energy (F4E) has worked together with the Culham Centre for Fusion Energy (CCFE), the host and operator of JET, for the provision of user experiences related to the integrated commissioning of the tokamak. This work presents and discusses the main results and the methods that were used to extract and translate the commissioning experience information into ITER requirements.