AWS Elastic Beanstalk app initial access is not secure, but subsequent redirect is

I am using Elastic Beanstalk (with load balancer) to support a Wordpress site. I have setup SSL through the Certificate Manager (ACM) and enabled the load balancer to listen on Port 443 for HTTPS. I have also tried to force HTTPS on my Wordpress site by adding the following lines to the wp_config.php in my source bundle (as suggested by many posts):

define('WP_HOME','https://example.com');
define('WP_SITEURL','https://example.com');
if (strpos($_SERVER['HTTP_X_FORWARDED_PROTO'], 'https') !== false)
       $_SERVER['HTTPS']='on';

However, my problem is that when I try to access my site, the initial access is not secure, ie a HTTP connection, but when I try to navigate to other pages and back on my site, the connection immediately becomes a secure HTTPS connection. I am wondering what can I do to resolve this issue such that upon initial access to the site, HTTPS is forced. I also ran into "Too many redirects" errors before because of trying to force HTTPS and Wordpress makes it a bit tricky doing that, so I am trying to avoid that. Any help is much appreciated. Thanks!