The time it takes for your site to be delisted from a blacklist will actually depend on who is blacklisting your site.
As soon as we’re done removing all malware from your site, we will get in touch with Google, McAfee, Yandex, Norton or are any other blacklisting agency asking for a review of your site.
Some companies are faster than others, but they usually take from three to five business days to remove sites from their blacklists and there is no way to speed up this process. Once the search engine has reviewed the request, warnings presented on your website and in search results should disappear.
If your search engine results were modified by attackers then you will have to wait for search engines to re-crawl your website. Using Google Search Console / Webmaster Tools and other search engine dashboards, you can often request a crawl of your site to speed up this process.
Sucuri Labs is usually fast to delist sites, taking around four hours to review sites.Google is also fast, taking around 24 to 72 hours to have the site removed from their blacklist.