Do you want to stop recording prcoessing while classes are going on?
Normally, the BigBlueButton server begins processing the data recorded in a session soon after the session finishes.
However, you can change the timing for processing by stopping recordings process before beginning of classes and restarting it after ending of classes.
This ensures that all server resources are dedicated to ongoing classes.

crontab -e
# Add the following entries
# Stop recording at 7 AM during week days
0 7 * * 1-5 systemctl stop bbb-rap-process-worker.service bbb-record-core.timer
# Start recording at 6 PM during week days; bbb-record-core will automatically launch all workers required for processing
0 18 * * 1-5 systemctl start bbb-record-core.timer

Try out the above optimizations and tell me if you are able reschedule recordings, and, in turn, improve your user experience.