Usually very close to instant, and your post above appeared quickly, I presume. No idea what happened to the post you refer to, could have been posted during a server timeout, which happens now and then on any forum, been quite stable here lately. After posting, your browser should quite immediately take you to the new post, if not showing after a while just repost, and don't worry about duplicates etc, as any topic, post or content can be cleaned up.
& remember this:
http://www.audioworld.net/BSA/forum/index.php/topic,2483.0.html