There are benefits of using installing drupal via composer.
composer create-project drupal-composer/drupal-project:8.x-dev myproj
# you can now add the required plugins eg
composer require drupal drupal/devel:8.*
Forget about drush, let us use the drupal console to install the site. This is the symfony way.
# let us configure the drupal command line
ln -s /path_to_myproj/vendor/drupal/console/bin/drupal /usr/local/bin/drupal