There's no set period of time you have to wait for it to be listed. In fact, we don't even promise to list it, although we want to add as many quality sites to our directory as we can.
Your site may be tomorrow, next week, or next July. We don't know. It depends on when an editor gets to it.
Our policy is to only give status reports once every six months as explained
here.
Since you can check for yourself to see if the site has been listed, the only value in a follow-up check is to make sure we didn't either decide to not list the site at all or accidentally delete the submission without reviewing it. We don't need to do that every month. We've set a limit of once every 6 months.
This helps us focus on editing. If your site is reviewed and accepted, you'll see it show up in the directory. If it doesn't you may ask for another status check on or after January 15.