If you want to do it with JavaScript like your first attempt, you should have something like this:
<div ng-app="app">
<span id="dateHere"></span> - {{fileName}}
<script>
document.getElementById("dateHere").innerHTML = Date();
</script>
</div>
and if you want to have more control on your date format:
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.4.4/angular.min.js"></script>
<div ng-app='app' ng-controller='Ctrl'>
<span id="dateHere"></span> - {{fileName}}
<script>
document.getElementById("dateHere").innerHTML = Date();
var date = new Date();
var currentYear = date.getFullYear();
var currentMonth = date.getMonth();
var currentDate = date.getDate();
var customDate = currentMonth + '-' + currentDate + '-' + currentYear;
document.getElementById("dateHere").innerHTML = customDate;
</script>
</div>
<script>
angular.module('app', []).controller('Ctrl', function($scope){
$scope.fileName = 'your file name';
})
</script>
-> on Plunker