Stan,
Everything is online, you should go to recreation.gov website, register and get permits. I'm fishing already for a two months there and got all but one ticket for my group. I think there are very good chances that you get your permit (overnight or all day). As for this moment, there are 32 available day permits available for September 21st. As your hiking day approaches, keep trying to refresh window as permits appear and quickly disappear.
Good luck!
