Why don’t reviews appear right away?

Publication of reviews in the app stores takes 1 to 48 hours. This means that after writing the texts will appear in the app store after a while. On average, it takes about 30-48 hours for a review to appear on Google Play or Apple AppStore. 

The minimum period for the first reviews to appear on the Google Play after launch: 12 hours.
The minimum period for the first reviews to appear on the AppStore after launch: 30 hours.