Concatenating 2 columns with TimeStamp in JavaScript Add Method

I have a Save button- when user clicks it i want a new value of concatenation of 2 columns with time stamp. Below is the image of the list. I want the Recipient column to be loaded with BillingDoc+Item+TimeStamp

Here is my code

function AddItem() {
    var ListItem = web.get_lists().getByTitle('TracingList');
    var itemCreationInfo = new SP.ListItemCreationInformation();
    this.oListItem = ListItem.addItem(itemCreationInfo);
    oListItem.set_item('Recepient', '??What Goes Here???');

    oListItem.update();

    context.load(oListItem);
    context.executeQueryAsync(ListQS, ListQF);

}

Any help is appreciated.