onInitialized is not totally initialized

[FVZGmbH]

I try to point the filter of the multiselect to add some stuff. But as it seems the child nodes are not in DOM at this time.
I use a specific template for the filter.

jQuery('select[multiple="multiple"]').multiselect({
		buttonWidth: '300px',
		enableCaseInsensitiveFiltering: true,
		filterPlaceholder: 'Filtern...',
		includeSelectAllOption: true,
		selectAllJustVisible: true,
		buttonTextAlignment: 'start',
		selectAllText: 'Alle auswählen',
		allSelectedText: 'Alle ausgewählt',
		nonSelectedText: 'Auswählen',
		nSelectedText: ' ausgewählt',
		buttonClass:' form-select text-start',
		templates: {
			filter: '<div class="multiselect-filter d-flex align-items-center"><i class="fas fa-sm fa-search text-muted"></i><input type="search" class="multiselect-search form-control" data-selectAllText-original="Alle auswählen"  data-selectAllText-filtered="Alle gefilterten auswählen" /></div>'
		},
		onInitialized: function(select, container) {
			console.log(container.children('.multiselect-container').children().length) // result: 0, should be count of select->options plus 1 (the filter tag) 
	}
});

I can't find any solution to wait till everything is in place to alter some things