Please look at the bottom line in the image. What you said is pretty much what it says.
How can I disable start of missed backups when duplicati start? is a Features topic with ideas.
Add ability to skip missed scheduled backups #3251 which it mentioned has other discussions.
Issue is not closed though, which I take to mean there’s no easy option to get what you’re after.
How can I stop a stuck backup job in Duplicati without uninstalling the entire program?
talks about a very convoluted method, but basically catchup-at-start is sometimes a pain to get.
Using Settings to pause a little while (to allow for manual work) helps, but is not a great answer.
There are also some bugs (I think) where changing schedule in GUI doesn’t clear old schedule.