The Forum has a calendar link within the blue menu bar at the top of the page. If you click on it, you may find other Forum members who might be leaving Sarria around your time frame of departure. You can also add your name to the calendar as well. . This link will tell you how
Sarria is at the top of the list of favorite starting places for those walking Camino Frances, so if you do not find someone on the Forum to walk with, you will have a lot of fellow pilgrims with whom you can get to know.