T.M.
It is really rough but important to get them in the mode of organization. So many things will be required of them in the coming years. For my 9 year old son I make sure there is routine. He is still working out the kinks but he is realizing that I won't pick up all the pieces when he leves things at homes or at dad's that he is neededing/wanting.
Every evening when he has complted his homework everything goes back into his backpack.
In the morning he is to start getting dressed directly 1 hour before we leave and verify lunch options right after breakfast then that his backpack and jacket are ready to roll out the door. When we began the process of the routines I had charts/checklists for him to look at to remind him rather than me being the harping bad guy.
I am a working mom so I have to be getting myself ready in the AM as well and this has made him feel more responsible and once in the routine he really likes the organization and the reassurance that it gives him! I hope that maybe sometihng like this might work for you and your son. Good Luck.