If only people would listen to this advice. The number of times I have started a project by trying to think about the data model only to get told "just build the models, we can change it later" drives me insane. Code is easy to change, your data model is not once it is in production.

Only if you use a single, concrete data model. If your domain supports the use of something like event sourcing, your "data model" is surprisingly easy to change. Or in this case, is = are, and data model = data models, and they're actually derived from your domain events, which can be replayed. At any time.

testify Brother/Sister Testify