There are two reporting periods, during the second and fourth years. It is highly advisable to carefully read the instructions corresponding to your own call, as some aspects may vary from call to call.
The documents and information regarding the reporting can be found at:
Moreover, it is interesting to read the information contained in this FAQ:
http://www.anirc.com/faq/#should-i-do-something-to-apply-for-an-i3-evaluation