We are also cruising in April on NCL and prepaid for our parking using the parkwhiz.com site last month. Our parking pass is already printed out and ready to put on the dashboard, so I am hoping we are all set. I did try to do a mock booking recently because another cruiser was having an issue with trying to prepay for parking and the site would not allow me to. I believe the parking lot at the pier is already sold out and I am not sure about the status of the other parking options near the pier.