lynt_date_shortcode.php

function lynt_date_shortcode( $atts , $content = null ) {

$atts = shortcode_atts(
  array(
    'den' => 0,
    'start' => '',
    'stop' => '',
   ),
  $atts,'lynt_date');

$den = intval($atts["den"]);
$start = strtotime($atts["start"]);
$stop = strtotime($atts["stop"]);
$ted = time();

if($ted > $start && $ted < $stop && intval(date('N',$ted)) === $den) {
  return $content;
}

}
add_shortcode( 'lynt_date', 'lynt_date_shortcode' );

//[lynt_date den="5" start="17:30" stop="21:00"]TEXT[/lynt_date]