Checkbox for initial sending

Was wondering how to transform this plugin a bit: just use the manual “resend” that appears after an hour… so automatic sending would not happen unless the same field or a similar one in the publish box is ticked. And of course no delay for it to be there. That would be an interesting feature because maybe not all posts are worth to be sent… I checked the code, and so where is a check to see if the post was sent already… That’s a start ! But that would be great to have and another condition (field) for the first sending ! Any help welcome.