Add `current_day` marcos to jet-engine

add_filter( 'jet-engine/listings/macros-list', '__your_prefix_add_jet_engine_new_marcos' );

function __your_prefix_add_jet_engine_new_marcos( $list ) {
	$list['current_day'] = '__your_prefix_jet_engine_current_day_cb';

	return $list;
}

function __your_prefix_jet_engine_current_day_cb() {
	return mktime( 0, 0, 0, date( 'n' ), date( 'j' ), date( 'Y' ) );
}