2. Another group say that RFC should appear just before deployment of a change solution (administrator wants to deploy a new version of the application).
I would agree with #1. - RfC should be introduced once there is a need for a change. Once you are ready for the implementation - many activities were already performed. In order to have all needed information - RfC is needed.
Following an ITIL Service Portfolio Management process (SPM) there can found 4 types of process initiators (Strategic iniciative, Request from business, Service improvement and Service suggestion). We call all of them as "iniciatives", not requests for change (RFC). So when business wants to change an application, it is not called RFC from the beginning. It is called INI.
The change proposal is introduced in the 3rd activity of SPM process (approve), when authorisation from a change management is needed to proceed the INI to implementation project (covering design & transition phases of new/changed services). After having accepted of the new/changed services the RFC are generated in order to authorise a deployment of new/changed services into a production environment (where "final changes" of CIs are performed).