Unfortunately, your picture doesn't show. But, so you know, signing the form adds nodes to the form - so you can't actually just add a rule to your signature group. If you take a look at one of your signed XML files in a text editor like Notepad++ you'll see a "Signature" node added to each of the signature groups (or multiple "Signature" nodes if the form is allowing multiple sigs).
I'm attaching a sample form - save it locally, right click the saved file and select Design to open in design mode. I've added a field with a default that counts the Signature nodes in one of my signature groups - and a button that sets another field based on how many signatures there are. So - preview, sign once, click the button, sign again, click the button. You'll see the "status" field change. You could do something similar in your submit rules - have a field w/ a default that counts signatures, and leverage that to set a status field.