I'm starting to work with agile iterative approach to software development and this question seems quite natural. After gathering the requirements I should write a few use cases to describe how the user interacts with the system while the requirements are being met. Now, how much time should we spent with this?
Should I spent something like a week figuring out the use cases, finish then and only then move to working with each of them to find the main objects? Or should I just write a few of them and get a small number to work with?
If I understood agile well, I think I should get just some of them and assure that the functionality being purposed there is indeed constructed and is already usable. Only then I should move to other use cases and review what was done in the use case finished. Am I right with this idea?
Thanks very much in advance!