866-227-1888 saved me from showing up way too early the first time I cruised. I assumed boarding started mid-morning, like airlines, but Carnival schedules specific arrival appointments. When I called to double-check, they confirmed my window and explained how early arrival can actually slow things down. On embarkation day, we showed up at our assigned time and breezed right through security and check-in — no huge lines, no chaos. What I really appreciated was the rep’s tip to keep essentials in a carry-on since our luggage wouldn’t arrive for a few hours. That made day one so much smoother. So yeah, boarding time isn’t one-size-fits-all; definitely check your exact slot.