AngularJS ngRepeat and orderBy.

HTML

<div ng-app="myApp" ng-controller="Ctrl">
    <div ng-repeat="card in myCards | orderBy:['estimatedStartDate','actualStartDate']">
        <businesscard>{{card.lastName}}</businesscard>
    </div>
</div>

JavaScript

angular.module('myApp', [])
    .controller('Ctrl', function($scope) {
        $scope.myCards = [
            {estimatedStartDate: null, actualStartDate: 'John', lastName: '3'},
            {estimatedStartDate: 'Eleanor', actualStartDate: null, lastName: '2'},
            {estimatedStartDate: 'Maxwell', actualStartDate: null, lastName: '4'},
            {estimatedStartDate: null, actualStartDate: 'Buzz', lastName: '1'},
            {estimatedStartDate: null, actualStartDate: 'Neil', lastName: '5'}
        ];
    });