I am with you. I listed one of my TS for rent on the site and it took 10 days for the listing to appear. JMB replied to my complaint saying that they are upgrading their site, yadda, yadda, yadda, and ads posting will be much faster in the future. I was not happy about it so I understand where you're coming from. Like you said, posting should be immediate, considering the cost of membership.
Good news is my TS is now rented and I hope it'll be the same for you.