title: Setting cookie through PHP when Contact Form 7 submited
body: <p>I'm working on a landing page made with Bootstrap 4, Wordpress and Contact Form 7 plugin. In the page I have 4 buttons that when clicked show the same Contact Form 7 pop up form. I want them to:</p>
  
  <ol>
  <li>Any of the 4 buttons clicked for the 1st time show the pop up with the form (already done).</li>
  <li>When the form submited and any of the buttons clicked again (could be the same one) do not show the form, but start a download of PDF document.</li>
  </ol>
  
  <p>I don't know how to design that better. I think that when the form is submited a cookie is set through PHP so I can check in each button if the form is done. Is it a good aproach? How should I set the cookie? Is there any other way?</p>