We recommend customers install release upgrades in their sandbox instance and test areas of the product they use.  In particular areas where they may have added custom Flows or custom code.

The general roll out sequence for our upgrades are:

1. Beta testing and regression testing performed in various test environments
2. We upgrade our internal instance
3. Publish to the AppExchange and notify those that are waiting on a particular piece of functionality
4. Send release communications schedule advising of Sandbox and Production release dates
5. Push updates to Sandbox
6. Push updates to Production (generally at least 2 weeks after sandbox and near to the next release being available)

See schedule upgrade dates for details of when Push Upgrades will occur.