user_profile_filter_profile_nav_default

You can set custom default active nav by filter hook.

function user_profile_filter_profile_nav_default($nav_default){

  $nav_default =  'about'; // nav index/id
  return $nav_default;

}

add_filter('user_profile_filter_profile_nav_default','user_profile_filter_profile_nav_default');

Default navs are

feed
about
followers
following