the beauty of agile delivery is that it is designed for uncertainty and change. things you didnt know before, things you just thought up, ideas you have whilst reviewing existing features frequently result in requests for change. rrsIT will help structure the near term prioritised features you want and recommend options in conjunction with your ideas and known requirements. using a combination of agreed online tools such as wireframing, mock up, sketching with pragmatic documentation, together we will plan out the iteration deliverables.
iterative planning is more lightweight than linear methods. from the businesses point of view, plan ahead far enough at least toward the next iteration. you don't want to be sitting in a meeting wondering what features you want next whilst we sit there in silence!
the next iteration may be some adjustments to the previous, or completely new features, depending on how far you are 'drilling down'. everyone is different. we would recommend you typically perform a high level sweep of a prototype features that dont have to work fully, and then refine it as you go, recording the finer detail features you want for later iterations.
meanwhile, the technical team will ensure all code in the IT shop is tidied up, documented where applicable and put into its repositories correctly.
at the end of the planning phase, you will have elaborated on the solution, possibly re-prioritised features, detailed in diagrams or documents on chosen features and agreed any further detail that must be provide to the technical team. the technical team now have the necessaries to start production.