We arrived about half an hour after the allotted time and found no queues. Staff were friendly and helpful. Bags were delivered to our cabin in a few minutes. Others we spoke to who arrived too early had not had a pleasant experience as they were not allowed to board, although there was a baggage drop area.
Would not recommend the cabins on deck 8 below the Lido above. Lots of noise from scraping chairs and tables and general foot traffic.