It can take months, and most of the time you have to submit it a few times. At the end of the day its people who decide if you get in, and some of them have motives for not letting you in - they may even run a particular category because they own a site in that category.

I have a few sites that have 3 or 4 listings each , but it has taken ages for that to happen, it certainly wont happen over night.