You MUST have reservations IN ADVANCE before arriving at NASKW. You cannot reserve specific sites - that part is true. But reservations are REQUIRED prior to arriving.
Rotation only occurs when there is a waiting list and rigs are in dry camp. If no one is waiting for a FHU site, then rotation is not underway. Once busy season fully kicks in, at that point rotation will be 14 days. In the meantime, you stay in FHU until your time is up for someone in dry camp to move to your site. That might be 14 days, 27 days, 44 days, etc. In summer low season, it could easily be 5 months or more before rotating.
Busiest time of year - it will become 14 days.