Just got back from the Miracle departing August 28th, Actual boarding was about 11:30, but people were there checking in and waiting to board by 10:30. Get on early if you want to get the Cabana at Half Moon Cay.
We boarded our last cruise at around 2:00 p.m. We drove from Orlando to Port Canaveral and once there I couldn't find the correct terminal and kept going around in circles. Once in the correct place, I dropped everybody off and parked the car. The line was extremely long, but it went by at a supersonic speed. How they do it, I will never know, but we were on board in less than an hour after standing in line.
Our cabins were ready when we got there. We dropped off our luggage and went up to the lido deck for lunch. Please keep in mind, that practically everyone has the same plan as you do, eat lunch as soon as boarding, the lines to the buffet and hot grill will be long.
If I'm not too late to post - we sailed the Miracle last year, got there around 11:30 but it was almost 1 by the time we boarded - 3 sections of folks waiting to board. I might venture a guess to say wait until 1:30 to come to port. We're on her on the 21st and will probably arrive same time as last year, but that's the schedule of limo company for 6 of us traveling. Have to say NYC pier seems to be horrible for boarding as brooklyn pier aboard Princess was an awesome experience. NCL was similiar delays in Manhattan but not as bad as Carnival ships. My mom was just in Port Canaveral in May aboard Glory and she commented that boarding and disembarking were no where near the difficulties we had last year.