<html>
<head></head>
<body>
  <div class="main">
    <div class="container">
      <form id="loginform">
        <div class="form-group">
          <div class="input-group">
            <span class="input-group-addon">
              <i class="material-icons">event</i>
            </span>
            <input class="form-control" type="text" id="releasdate" name="releasdate" autocomplete="off">
          </div>
        </div>
        

            <button type="button" class="btn dvalidate">Validieren</button>

      </form>
    </div>
    <div id="footer">
      <div class="footer-main">
        <a target="_blank" href="https://www.hepster.com"><img src="https://www.hepster.com/download/images/codedbyhepster.svg"></a>
      </div>
    </div>
  </div>
</body>

</html>
/*for the pen*/
html, body{
  background-color:#ddd;
  width:100%;
  height:100%;
  overflow-x:hidden;
  position:relative;
  margin:0;
  padding:0;
}
body *{
  font-size:16px;
  font-family:"Roboto";
}
body{
  transition:0.4s background ease-out;
}
body.valid{
  background:#47cf73;
}
body.invalid{
  background:#ff3c41;
}
h2{
    font-weight: 300;
    font-size: 30px;
    margin: 20px 0 0 0;
    border-bottom: 1px solid #ccc;
    padding: 20px;
    color: #0095de;
    background: #ffffff;
}
p{
  padding:10px 20px;
}
.main{
  width:100%;
  display:block;
  overflow:hidden;
}
.container{
  width:500px;
  margin:100px auto;
  background:#ffffff;
  box-shadow:0 12px 22px -12px rgba(0,0,0,0.15);
  border-radius:5px;
}
#footer{
  background:#fff;
  position:absolute;
  bottom:0px;
  width:100%;
  bottom:0;
  box-shadow:inset 0 1px 1px rgba(0,0,0,0.2);
  padding:6px 0 0 0;
}
#footer .footer-main{
  width:300px;
  margin:0 auto;
  text-align:center;
}
#footer .footer-main a{
  display:inline-block;
  width:200px;
}
#footer .footer-main a img{
  width:200px;
  display:block;
}
/*the form*/
form{
  padding:20px 0;
}
.form-group{
    padding: 0;
}
.form-group:first-child{
  margin-bottom:0;
}
.btn-primary{
  cursor:pointer;
}
.margin-top-20{
  margin-top:20px;
}
input#releasdate{
  padding-right:100px;
}
.btn.dvalidate{
    position: absolute;
    top: 22px;
    z-index: 100;
    right: 17px;
}
$(document).ready(function(){
  $('#releasdate').datepicker({
    autoclose:true,
    language:"de-DE",
    format:"dd.mm.yyyy"
  }).on("changeDate", function(e) {
        $(".dvalidate").click();
    });
  $('#releasdate').datepicker("setDate",new Date());
  
  $(".dvalidate").click(function(e){
    var releasedate = $('#releasdate').datepicker("getDate");
    releasedate.setHours(0,0,1);
    var now = new Date();
    now.setHours(0,0,0);
    console.log(now);
    console.log(releasedate);
    if(now > releasedate){
      $(".input-group-addon i").text("event_busy");
      $("body").addClass("invalid").removeClass("valid");
      console.log("not valid");
    }else{
      $(".input-group-addon i").text("event_available");
      $("body").addClass("valid").removeClass("invalid");
      console.log("valid");
    }
    
  });
  
  setTimeout(function(){
    $(".dvalidate").click();
  },200);
  
  
});

Run Pen

External CSS

  1. https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.0.0-alpha.6/css/bootstrap.min.css
  2. https://cdnjs.cloudflare.com/ajax/libs/bootstrap-datepicker/1.6.4/css/bootstrap-datepicker.min.css

External JavaScript

  1. https://cdnjs.cloudflare.com/ajax/libs/jquery/3.1.1/jquery.min.js
  2. https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.0.0-alpha.6/js/bootstrap.min.js
  3. https://cdnjs.cloudflare.com/ajax/libs/bootstrap-datepicker/1.6.4/js/bootstrap-datepicker.min.js
  4. https://cdnjs.cloudflare.com/ajax/libs/bootstrap-datepicker/1.6.4/locales/bootstrap-datepicker.de.min.js