Add Option Tree Metabox to Specific Page Template Only

$post_id = $_GET['post'] ? $_GET['post'] : $_POST['post_ID'];
$template_file = get_post_meta($post_id, '_wp_page_template', TRUE);

if ($template_file == 'welcome.php') {
    ot_register_meta_box( $home_page_meta_box );
}



/* -------------------------------------------------------------
so, entire file should looks like this: 
------------------------------------------------------------- */


<?php
/**
 * Initialize the meta boxes. 
 */
add_action( 'admin_init', '_custom_meta_boxes' );

/**
 * Meta Boxes demo code.
 *
 * You can find all the available option types
 * in demo-theme-options.php.
 *
 * @return    void
 *
 * @access    private
 * @since     2.0
 */
function _custom_meta_boxes() {
  
  /**
   * Create a custom meta boxes array that we pass to 
   * the OptionTree Meta Box API Class.
   */

    $header_image = array(
    'id'          => 'header_overlay_content',
    'title'       => 'Header Content',
    'pages'       => array( 'page'),
    'context'     => 'normal',
    'priority'    => 'high',
    'fields'      => array(
      array(
        'label'       => 'Header Area',
        'id'          => 'header_content_overlay',
        'type'        => 'textarea',
      )
    )
  );
  
  /**
   * Register our meta boxes using the 
   * ot_register_meta_box() function.
   */
  ot_register_meta_box( $header_image );
  
  $home_page_meta_box = array(
    'id'          => 'home_setting',
    'title'       => 'Home Page Content',
    'desc'        => '',
	'pages'       => array( 'page' ),
    'context'     => 'normal',
    'fields'      => array(
      array(
        'label'       => 'Location',
        'id'          => 'location',
        'type'        => 'text',
        'desc'        => '',
        'std'         => '',
        'rows'        => '',
        'post_type'   => '',
        'taxonomy'    => '',
        'class'       => ''
      ),
      array(
        'label'       => 'Registration Link',
        'id'          => 'register_link',
        'type'        => 'text',
        'desc'        => '',
        'std'         => '',
        'rows'        => '',
        'post_type'   => '',
        'taxonomy'    => '',
        'class'       => ''
      ),
      array(
        'label'       => 'Banner Image Link',
        'id'          => 'banner_img',
        'type'        => 'upload',
        'desc'        => '',
        'std'         => '',
        'rows'        => '',
        'post_type'   => '',
        'taxonomy'    => '',
        'class'       => ''
      ),
	  array(
        'label'       => 'Left Column Content',
        'id'          => 'left_c',
        'type'        => 'textarea',
        'desc'        => '',
        'std'         => '',
        'rows'        => '',
        'post_type'   => '',
        'taxonomy'    => '',
        'class'       => ''
      ),
	  array(
        'label'       => 'Center Column Content',
        'id'          => 'center_c',
        'type'        => 'textarea',
        'desc'        => '',
        'std'         => '',
        'rows'        => '',
        'post_type'   => '',
        'taxonomy'    => '',
        'class'       => ''
      ),
	  array(
        'label'       => 'Right Column Content',
        'id'          => 'right_c',
        'type'        => 'textarea',
        'desc'        => '',
        'std'         => '',
        'rows'        => '',
        'post_type'   => '',
        'taxonomy'    => '',
        'class'       => ''
      )
    )
  );
  
$post_id = $_GET['post'] ? $_GET['post'] : $_POST['post_ID'];
$template_file = get_post_meta($post_id, '_wp_page_template', TRUE);

if ($template_file == 'welcome.php') {
    ot_register_meta_box( $home_page_meta_box );
}

}