Here are the deadlines:
11.8 Presentation of alpha version of product
This means the product (gadget) should be in a state where 80% of the planned functionality is programmed. The product can have bugs, and rough UI, but it still should have a UI that is very much like the final UI.
22.9 Presentation of final version of product
This is the finished product, after all bug fixes, UI improvements, and of course features. The grade is based on this presentation.