Are there any consequences to getting to the port after your Port Arrival Time (such as showing at noon for a 10:30 time)? If not, is there any reason not to just pick the earliest time possible? In the past we have over-thought things and tried to figure out the exact time we expect to get there based on breakfast, packing, getting a uber/shuttle, etc, but if we know that we can be there any time after our PAT then we won't stress about being "on time" (although knowing us we will be there a few minutes before the time anyhow because that is just how we tend to roll)