What I do on CB is figure 1/4 inch per day. So.... if it is an inch and a half to the middle... I would cure it 6 or 7 days.... 7 days is generally how long I end up with on a full size loin. A little over isn't going to hurt anything.
You cann't over cure the loin and you so could leave it alittle longer if you want I have left one for about 12 days before and it tasted just fine and was cured very well. Just make sure that yourub and squeeze it on a daily basis and turn it over a few times too.