It depends on the meeting length and number of audio files - meaning, the number of participants who recorded the meeting.
After the meeting ends, file processing will begin in 30 minutes. Why the wait? Assistant wants to be sure that the recordings, from all participants, were stopped and submitted. The processing takes about as long as the length of the meeting. For example, if you attended a ½ hour meeting from 9-9:30 a.m., then the meeting minutes would be ready at 10:30 a.m. (30 minutes + the meeting length). However, more participants in the meeting means more time for processing.
The rule of thumb is that you’ll find the minutes in the Assistant after: 30 minutes + the length of the meeting.
But you don’t need to sit and wait ... when the meeting minutes are ready in Assistant, you will be notified via email.