Delete files / folders before scheduled transfer


I'm using SmartFTP to automatically back up my server data to an FTP server.

Here's what I did so far:
  1. Stop the transfer queue
  2. Copy all folders to the FTP Server
  3. Select all queue entries and click on "Schedule" in the context menu
  4. Selected "Instanciate" (or similar) as trigger
  5. Set SmartFTP to run the queue on startup and close when it's finished
This configuration works fine so far, but what happens if a source file is deleted *after* one or more backups have been made? It would remain on the FTP server forever I guess.

My question is: Is there a way to delete a destination folder prior to uploading the source folder? I tried to schedule a deletion with the same steps as above but it always runs immediately - even though the queue is stopped.

Any advice would be appreciated.