Tirupati same-day darshan (HYD → TIR) – need advice

Hi everyone

Flying Hyderabad to Tirupati (8 AM → 10 AM arrival) with my wife, return at 9 PM same day.

Didn’t book Srivani darshan.

Options:

Try booking online at 12 AM (May 9)
Try getting tickets at Tirupati airport

Is airport quota reliable? If I get tickets after landing, can I finish climbing steps, darshan and still catch 9 PM flight?

Anyone done same-day darshan like this?