New customers will automatically be opened in the Swiss data center. 
Currently, existing customers will receive an automated email from Microsoft for Release 18.3, suggesting a date for the automated update to Release 18.3. You can adjust the update date to your needs. With the release upgrade, your data will automatically be moved to the Swiss data center. 

To be able to control what happens with your data, you can first update a sandbox to Release 18.3 for test purposes and will then see the entry 'Switzerland North' under 'Azure Region'.

You can check the location of your data in your Admin Center at any time:

Screenshot Azure Region

We are very pleased to be able to offer our existing SwissSalary 365 SaaS cloud customers the Swiss data center without any additional effort or cost.