Hi Beko, there is no mechanism to stop a running backup that takes more than X amount of time. It is true that initial backups can take a while. If your goal is to minimize how it affects your bandwidth during the day, then you can experiment with throttling options. You can’t have different throttling options at night vs at day though.
A more robust way to handle this is at your router by using QoS. That’s personally what I do - deprioritize backup traffic so that it consumes as much as it needs but will be scaled back automatically by other, non-backup traffic.