As has become customary in recent core updates Google made the accouchement before actually starting to roll out the update. Whilst this gives webmasters an advanced warning of potential performance volatility, there is nothing that can be done in the time between the announcement and the rollout to change how a site will be impacted.
As with all core updates, the advice from Google remains, do everything possible to provide the best user experience on your website and create the most knowledgeable content to improve performance or reverse a declining performance.
What has been unique about this core update is that Google also announced a July version of the core update at the same time. Historically there will be a couple of months between core updates so having one so soon after the June update, and announcing it so early is a step away from the norm for Google.
It is believed that this was intended to be one core update but parts of it were not quite ready to be released and instead of delaying the full release, Google decided to go ahead and roll out the update in two parts. Many might not see this as ideal however some comfort can be taken from Google's statement, ‘Of course, any core update can produce drops or gains for some content. Because of the two-part nature of this release, it’s possible a very small slice of content might see changes that reverse in July’