I'd throw in an extra day for contingencies. Until you try trail hiking with full pack, you really won't know. That's why I suggested dayhiking with a full pack first, to find out what you can do. If you're almost there with a day left, you can find a nice place to camp and just relax. Of course, if you have cell phone coverage out on the trail (we seldom do out here in the western mountains), you can call if you're ahead of schedule.