How to automate posts messages for different companies based on the release version update

Context: showing newly released features as a popup when user signed in to the application. I will be using Posts message option.

Scenario: multiple customers (company / organisation) will be having different release version of a product. when a new version is released with new features, initially we will be releasing this version only to some of the customers (company / organisation) and after few days (cannot be specify how many days) will be releasing to another bunch of customers. the query here is once the posts message is setup how to push the posts messages to the customers upgraded to the latest version.