Actually it will be Friday-Sunday, July 19-21.

It will not show on the calendar for a week but sign up anyway (https://www.yosemitehg.org/calendar) so that you have first options on flying. There aren’t any other trips on the calendar so I would expect this to fill up quickly.

BTW: Having a confirmation for flying gives you a reservation to get into Yosemite with their new rules requiring either reservations or lodging confirmation.