To add (system) date and time into the report, I *think* you have to user Report Builder and add appropriate field(s) in the Paper Layout. Honestly, I've never heard of such a utility that would add this data during the runtime. It *might* exist, but I don't know anything about it.
However, there is possibility to RUN (not edit) a report from the command line, without opening it in the Report Builder. Command line should look like this (or its modifications) (MS Windows version):