is_singular() not working

The problem is this simple: it doesn’t work. The code is:

/** custom post types */
function create_post_type() {
  //projects
  register_post_type( 'project',
    array(
      'labels' => array(
        'name' => __( 'Projects' ),
        'singular_name' => __( 'Project' )
      ),
      'public' => true,
      'hierarchical' => true,
      'supports' => array('title','editor','thumbnail','custom-fields','page-attributes')
    )
  );
}
add_action( 'init', 'create_post_type' );

/** scripts */
function my_init_method() {
    if(is_singular('project')) {
        wp_deregister_script( 'jquery-topup' );
        wp_register_script( 'jquery-topup', 'https://gettopup.com/releases/latest/top_up-min.js');
        wp_enqueue_script( 'jquery-topup' );
    }
}    

add_action('init', 'my_init_method');

When I render a single post of type project, the script is not called, whereas if I set the if(true) it does appear. Even the is_singular() doesn’t render in single pages.

Any known issue?

Thank you