The builder should have this information from his/her phase I flight test data. While it isn't required to have a Pilot's Operating Manul (POM), it wouldn't be a bad idea to write one yourself if you don't have one from, among other things, data collected during flight testing. Hopefully this information was recorded somewhere and you can get it without repeating these tests. There are good examples on this website of documented POM's. You can tailor it to your airplane.