How can I set custom field date field for default date to be today's date?
I am not sure if this is possible through UI configuration. The form only allows you to enter valid date but not now(), CURRENT_DATE() etc. However it is definitely possible by adding a small code in a extension.


Create and enable a new CiviCRM extension
Implement the hook_civicrm_buildForm in your extension


For the appropriate variable do:

function ext_civicrm_buildForm($formName, &amp;$form) {
  if ($formName == 'REPLACE_WITH_FORMNAME') {
    $defaultDate = [];
    CRM_Utils_Date::getAllDefaultValues($defaultDate);
    $defaults['custom_XXX'] = $defaultDate;
    $form-&gt;setDefaults($defaults);
  }
}