Hi
I want to add in Mr. Lakshami's post that you need to maintain this item category in manual item category selection in VOV4. For billing plan you can study on help.sap and there are lot of discussions on SCN. In billing plan you can enter dates mannualy and assign a blokcing reason according to your requirement so that billing can not be done before actual date.
Do some work and effort at your end let us know if you get stuck. Take help from Google
Thank$