Abrir um modal por 5 segundos ao abrir a tela
<script type="text/javascript" src="https://code.jquery.com/jquery-1.12.1.min.js"></script>
<script src="https://netdna.bootstrapcdn.com/bootstrap/3.1.1/js/bootstrap.min.js"></script>
<link href="https://netdna.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap.min.css" rel="stylesheet" type="text/css" />
<div class="modal fade" id="overlay">
<div class="modal-dialog">
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-hidden="true">×</button>
<h4 class="modal-title">Modal title</h4>
</div>
<div class="modal-body">
<p>Context here</p>
</div>
</div>
</div>
</div>
<script>
$('#overlay').modal('show');
setTimeout(function () {
$('#overlay').modal('hide');
}, 5000);
</script>
