SunSet+Zoom + Time

When I try to capture a sunset, I place the sun in the upper left corner of the view finder
But if you want the sun to be as large as possible, you would need to know the zoom factor you would use and what time to start
I just have dslr cameras that zoom up to 300mm
There must be endless settings , but I just need one hypothetical **
*** Time before sunset to start

*** Zoom factor**
*** Frames per sec**
Thanks