We currently only populate these properties when the GetPackageMetadata target is run, which is part of the Pack/GetPackageContents call chain. If you want to use these properties earlier, however (such as in assembly metadata or some ThisAssembly constants), you need to tweak the build to force it to run.

It's better if we also run our property inits whenever the InitializeSourceControlInformation target runs, which will typically be before assembly info/version generation is run, which is early enough for most usages.