Google can take quite some time in order to index and show the rich snippets. From my own experience and online responses it can take up to 2~4 months before a search engine like Google shows the rich snippets on the listings.
Having this plugin enabled doesn’t guarantee it will show up, as Google still has its own algorithm on when to show them or not.
I believe you can influence the chance of having it show up by consistently writing new content and reviews, helping the search engine identify you as a up-to-date authority on whatever you’re doing.
What if the rich snippets aren’t showing up?
As this is still quite a new plugin there are probably still improvements to be made. If you’re actively publishing reviews and the rich snippets aren’t showing up (yet), please get in touch through the Reviewer website so we can verify if everything is setup correctly or if needed troubleshoot. https://wpreviewer.com/support/