vue-good-table custom sorting - vue.js

Question

I am using vue-good-table and have the following code so far:
<vue-good-table :columns="columns" :rows="rows"
styleClass="vgt-table condensed striped bordered"
:sort-options="sortOptions"
:search-options="searchOptions"
:select-options="selectOptions"
#on-selected-rows-change="selectionChanged">
</vue-good-table>
sortOptions: {
enabled: true,
initialSortBy: { field: "date", type: "desc" },
}
columns() {
return [
{
label: "Name",
field: "name",
},
{
label: "CreationDate",
field: "date",
type: "date",
formatFn: function (value) {
return value != null ? moment(value).format('YYYY-MM-DD') : null;
},
sortFn(x, y) {
x = moment(x);
y = moment(y);
return x.unix() < y.unix() ? -1 : x.unix() > y.unix() ? 1 : 0;
},
},
]
}
Sorting works fine so far, and there are three states: 'asc', 'desc' and 'none'.
However i would like to achieve the following:
When clicking the column header and the current sorting type is 'none' for any of the columns, i would like to have the data sorted as defined in the initialSortBy property in the sortOptions. So sorted by date in desc order.
I tried using the #on-sort-change event but don't really know how to proceed further as i am quite new to Vue.
onSortChange(params) {
console.log('on-sort-change:');
console.log(params[0].field)
console.log(params[0].type)
if (params[0].type == 'none') {
console.log("default sort")
//TODO sort data as defined in initial sort
}
}