In the create release form there is no start and end date. I think that having the option to define these dates would be more user friendly and help in faster configuring the phases afterwards (their dates).
Thank you for the idea. When creating a release, you define a release date. The start date of the release is then automatically calculated based on the duration of the phases within. One suggestion to streamline the setup process would be to leverage release templates, which allow you to set the typical length of each phase and create the schedule accordingly when the release is created.
At this time we are not planning to make changes to the way release start dates are created. We hope you understand.