The precondition for reporting is the signature of the Grant Agreement by the Coordinator and the EU Services.
There's five types of monitoring, reporting and payments in the Grant Management Services in the Funding & Tenders Portal:
Continuous Reporting: available from the beginning of a project
Periodic Reporting: available at the end of a reporting period
Beneficiary Termination Reporting: started as soon as the termination date is reached
Scientific Reporting: only for ERC grants