Getting a listing isn't something you can do, period. "No site is guaranteed a listing -- no conceivable series of actions will get a listing!"
But it takes only a few minutes -- I'd think no more than 20 at the worst -- to request a review (a request that will be granted, according to the social contract.) That time includes reading the submittal policies (and who does that anyway, sigh?), finding the right category (some people do this, thanks...) and writing some title and description in the submittal form.
Then it takes about the same amount of time on the editors' side -- typically two to twenty minutes.
The six months is a limitation on forum posts, to keep importunate serp perps from hogging the forum. It's calibrated by the number of requests we get, and the number of volunteers we have to handle them. It has nothing to do with "time from submittal to review" over at dmoz.org.
But the editors are all doing something else (presumably something important to them). You're free to do the same. When some editor thinks your target category is the most important thing to work on, it'll be worked on. That decision doesn't depend on how long it's been since some other editor made the same decision.
