я решил:
<?php
if ($model->isNewRecord) {
$form->field($model, 'erstellt_am')->widget(DatePicker::classname(),[
'options' => [ 'value' => date('Y-m-d')],
'pluginOptions' => [
'autoclose' => true,
'format' => 'yyyy-mm-dd',
'todayHighlight' => true,
'todayBtn' => true,
'timeZone' => 'Europe/Amsterdam',
]
])
}
?>
Спасибо