One thing that proves to be a massive help in determining the lifecycle of products from Apple is the stringent patterns they have adhered to for a long time. So a lot can be surmised by taking a look at the history of the beta releases for the iOS platforms over the last decade. In 2017, Apple announced the iOS 11 at the WWDC keynote event on June 5, with the release taking place a few months later in September. The period in the middle was dedicated to the beta tests. This same pattern has been occurring over many years in the past.
So before we arrive at a plausible conclusion about the iOS 12 beta release and the iOS 12 final release, we need to take a look at the announcement and release pattern over the last decade. Find the chart detailing this pattern below.