Events are often done on the spot, with little to no thought at all. These are called 'pop-up' events and often players online at the time will participate in these types of events. We could possibly add a role in discord 'event-notifications', where players who OPT-IN to have the role are updated/notified if an event is going to take place on the server. Obviously it would work only for organised events, and not the random pop-up events that occur quite frequently.
It would not really be possible to set a date of an event, since the staff that can host these events all have different Time zones that may not match that of players on the server. So the best thing would to be mention the role - and state how many hours away the event will be on the server.
Example: @Event-Notifications || Event happening in 6 hrs || Event: Dodge the shamal.
That is the only possible idea I could think of.