So there are 3 ways of viewing the pandas for guests: Timed tickets, Standy line, and a paid BTS early morning experience.
The timed tickets are what you can get from the QR codes available only at the zoo during your visit. You will have a time slot you can go see the pandas with anyone else in the same time slot. It’s like a Fastpass for Disneyland rides.
Standby line is just that. You will have to wait in a queue by the exhibit as it looks like the panda exhibit will open around 9:30 AM. So you will have to wait and I can only imagine it will be quite the line.
And lastly a paid early morning experience. You get a tour before the zoo is open and an exclusive viewing of the pandas without crowds. Last I saw, it was sold out well into September and still selling out.
The link below is to the page with all I talked about
https://zoo.sandiegozoo.org/giant-pandas/visit