Created the shipping date field and added the date picker.
And disabled three days from the date they are ordering and also the previous dates (as we cannot have it ready by then).
By using the following code in the extension.
.extend(OrderWizardModulePaymentMethodPurchaseNumber.prototype, {
template: jj_shipping_date_shippingdate_tpl,
getContext: _.wrap(OrderWizardModulePaymentMethodPurchaseNumber.prototype.getContext, function(fn) {
var context = fn.apply(this, _.toArray(arguments).slice(1));
var today = new Date();
var dd = String(today.getDate()).padStart(2, '0');
var mm = String(today.getMonth() + 1).padStart(2, '0');
var yyyy = today.getFullYear();
today = yyyy + '-' + mm + '-' + (parseInt(dd) + 3)
console.log('date', today);
context.startDate = today
return context;
})
});