how can initializing datatable after take my data in FIREBASE?

I have a problem when I take my data from FireBase and tried to display this data in the data table, because datatable Initializes before

My code is this:

$(document).ready(function(){

firebase.database().ref('Usuarios').on('child_added',function(snapshot) {
    var dataSet = [[snapshot.key, snapshot.val().Nombre];

});

$('#myTable').DataTable({
    "bFilter": false,
    data: dataSet
});

});