It's not necessary especially since Etsy is not giving out incentives this year for having a certain number of RSVP. However, I would highly suggest you at least set up a Facebook event page and utilize it well. Don't just set it up and leave it there waiting for people to find it. Share it and have other share it...invite people to it, and make a flyer that has the link on it.
This way there is one central place that has all the information on it that people need to know; location, time, what it's about, what to expect, etc.