Oh my, Sara! You are definitely confused. As Saltydog wrote, you need the OVERNIGHT permit to do the Whitney hike and spend the night on the main trail. But each person only needs ONE permit, and you must start hiking on the "Entry Date" -- the date on the permit. Once you are IN on that entry date, you do not need any other permits.
Now, if you actually got reservations for Day Use permits, those are not good to spend a night sleeping along the trail. They will not let people camp on the trail even if they have two consecutive day use permits, either.
So if you have day use permits, you have the wrong permits. If you have overnight permits to enter on different dates, then you have too many. Either way, you need to call the Wilderness Permit Office at 760-873-2483, and talk over your situation. They might be able to help you some, and they will certainly be able to clear up some of the confusion.
Keep checking online, but do understand, the chances of some showing up are better one or two weeks before you hike.
