How long after you stop the pill will it take for you to O (ie if you stop it now will it start AF asap or will it take a week or so since you were only on it for so few days)? Or is that what you don't know.
I would split the difference between the 1st and 7th. For instance, stop the pill around the 4th, giving your body time to adjust and start AF (I am assuming that will take more than overnight). If you do start AF right away you will be due around the 10th but if not then it is giving you that much more cushion.
If you end up delivering earlier than 10-12 days then no amount of planning was going to help you anyway right (except maybe another month of BCP - which I don't suggest

).