Just a note on using any plugin to add timestamps. If you use RCON, depending how the timestamp is added by the plugin, the chat text will not show up in RCON.
When calling
in PlayerChatEvent will cancel the event totally in rcon from chat even being registered at all. It doesn't matter if you add date or whatever, any modification at all will not show up. In the server logs and game chat itself everything shows up fine. I did a simple test with no date prefixed at the start like the following:
rcon ignores it entirely.