Prevent Apple TestFlight from automatic testing at completion of build processing

We are using Apple's TestFlight for iOS testing. I have three App Store Connect (formerly called Internal) users and then groups of other testers for staff, private, public beta. When a build is uploaded with Application Loader it is processed, upon completion of processing it immediately starts testing and the App Store Connect Users get notified immediately of its availability.

How can we prevent going into automatic testing mode and also allow us to enter test notes before anyone gets a notification of this build, even the App Store Connect Users other than the submitter? This is essentially distributing a build for testing before we are ready and need more control over this.