Banner or Ad?

I just inherited a wordpress site and I’ve been able to address most of the big requests in short order.
I just got what seems like a simple request and I am looking for suggestions on a simple approach.
I need to put a reminder on the home page about an upcoming event.
I was thinking for something that came up…like a flashing banner or ad when the visitor came to the page initially….and perhaps vanished after a few seconds….or something along those lines.
There are a great number of plugins but I don’t always find demos of what the look like when deployed on the site…and many do not show how many downloads and installs there have been for that plugin.

Any suggestions would be greatly appreciated.

Thanks.