Unfortunately, there is still no statement from the major search engines as to whether, how and when rich snippets will appear in their search results. This makes it very difficult to give you an accurate answer. Here are some hints that might help:

• Snippets don’t appear after you click the save button in the plugin. Search engines need to crawl your site after you’ve added or changed your snippets. If you add snippets on a daily basis, the crawler will recognise changes more quickly than on other sites.
• Check that the Google Rich Snippets Test Tool doesn’t show any errors on your pages where you’ve added rich snippets. If there are errors, please check that your snippet is correct. Note that orange warnings are not errors. Rich Snippets should display if there are only warnings. However, they will not appear if there are red errors. You can read more about this in the linked article.
• Today, search engines use artificial intelligence to personalise search results. As a result, you may not see your snippet in search results, but other users may. Try clearing your browser’s internal cache and cookies, logging out of all services, and trying a new search to see if your snippet appears.
• If your snippet still does not appear, there may be other problems with your SEO quality. You should read through Google’s webmaster guidelines to get an idea of what might be wrong.
• Also check that you have read Google’s Structured Data Reference for a Schema and that you have followed the guidelines.
• Here is a very good blog post on SearchEngineJournal that explains why your rich snippets may not show up.