Hi Kevin,

 

At this time there is not a setting for dictating WHEN the signature will appear. By default, if your account is mapped to a specific signature, it will be visible on every compose window. For a case by case basis, you can use the lock icon from the toolbar to delete the signature text from the message body, or you can use the Signature dropdown from the top of the compose window to remove the signature from the message body. 

 

Since this isn't current functionality, I'll change this thread from a Question to an Idea so we can facilitate tracking on this request.