Publishing date and Auto Post

All working well for me apart from this feature, perhaps I am missing something.

I have scheduled some blogs to be posted on certain dates, and this does work. However, auto posting to my Twitter doesn't. The auto posting only seems to work when I post the blog immediately - is this true?

I would like to set my blogs to publish later in the week AND have them post to my Twitter account.

Image attached of setting.

Thanks