First Webinar - best day of the week?

I'm planning to host my first webinar—an introduction to my new reader magnet. I'd like to give my readers an opportunity to "meet" me and hear my voice and my heart behind the freebie. While not ideal as people may still be in “summer scatter,” I'd like to schedule this in August before school begins. What’s the best day of the week to host a webinar that people will actually plan to attend? Any experiential data you may have would be appreciated.

(In case you wonder, there is no ideal time of day as I expect an international audience.)