TOP > Various Settings of the Product > The Product's [Settings] Menu > [Interface] Menu > [Network] > [Services] > [Online Services] (SOS users only) > [Periodic Notification] (SOS users only) > [Weekday] (SOS users only)
Appears only if you have enabled the NTP function or installed the optional RTC kit, and if you have selected [Weekly] in the [Type] menu.