Media Scan on LMS 7.8.1 - 1441189259

I'm pretty sure on LMS 7.7.x (running on a Windows 7 box) I was able to set the time for a daily media scan of 'new and changed media files.' Now I am running 7.8.1 - 1441189259 and I can't find where that setting is. Or was. Can someone tell me how to get a media scan at 6:45 pm every day?

Thanks.