Validate required fields upon clicking the signature field in LiveCycle Designer

I am trying to figure out how to verify that all required fields are filled upon clicking the signature field. Currently, they are only being verified after the digital signature is added and the submit button is clicked.

Upon adding a digital signature, the form has you save it locally. We are finding that users are just emailing the saved signed copy rather than filling the required fields when the submit button is clicked.

I'm pretty new but am a quick learner.

Thank you.