Automate Timeshift for external hard drive

I would like to automate Timeshift under Debian. All the snapshots should go into an external hard drive. When I plug in my external hard drive Timeshift should automatically decide in the background if it's necessary to do a snapshot or if the daily snapshot is already taken (I might plug in the external hard drive several times a day). I couldn't find any solution in the Timeshift-GUI and I guess there is no? Then I thought to set up all the Timeshift-Settings in the Timeshift-GUI (e.g. the schedule) and create a snapshot with those settigs via a bash-script. At this point I couldn't find any hint how to create a snapshot through the terminal which uses the settings which I set up in the Timeshift-GUI. I would like to use those settings, because there are easy and quick to set up and I don't need to care for any logic how to delete which snapshots to keep their number small. Do you have any ideas for that or a completely other workaround for my problem? In this article an easy solution for Back In Time is given. I'm not sure if I should use BIT for my system snapshots because everyone recommends Timeshift...
https://askubuntu.com/questions/719031/how-to-make-silent-backups-when-plugging-in-a-usb-disk-and-when-using-back-in-ti I would like to know what you think about it. I'm quite new to all of that and the forum.