Originally Posted by jhowell
Regarding the automatic creation of a custom column for library availability: While several existing plugins rely on custom columns, I don’t know of any that automatically creates a custom column. Perhaps someone with more experience with the internals of Calibre could comment on this.
I wouldn't go there. The user will have a particular idea about what the column should be named, among other user preferences, like column location. They're going to end up in Preferences|Add custom column no matter what you do.
Instead, I'd suggest adding a paragraph to your help documentation explaining the steps.