DW and I plus grandkids stay at Fort Wilderness often. Here's some info to keep in mind.
Check-in typically is 1PM. (checkout is by 11AM which gives Disney a chance to determine what sites open up).
There is no overnight camping allowed in the parking lot. So, either stay at an off Disney RV park (KOA in Kissimmee comes to mind) or plan on arriving no earlier than noon.
If you arrive around noon and have not requested (through your reservation a specific loop) then you may get to check-in and go to your site.
The DISboard is a valuable site on all things Disney and the link below will help you further with Disney camping.
http://www.disboards.com/forumdisplay.php?f=24
Enjoy!!
Checking in at Fort Wilderness
