Update requests are usually a reasonably high priority for editors, because we like to know if a URL is dead, or a site has changed its content. Therefore, many volunteers try to review such requests promptly, but of course the timing depends, as always, on an editor being interested in the category, being able to edit there, and deciding to spend time there.
So I'm afraid there is no way of knowing how long it will be until someone reviews the request, or indeed if it will be accepted. It is certainly a good idea to make sure that your request reflects what can be seen
on the site itself, and that any changes you suggest to the listed title and description are in accordance with ODP guidelines.
A request full of hype and promotional language may be rejected by an editor at first sight, whereas if an effort has been made to follow the guidelines, and a clear reason given for the request, it is much more likely that an editor will take the time to check out the listing and perhaps make the necessary changes.