Call your T/A or the cruise line if you booked direct and find out when actual boarding will be allowed. You will not be able to board the ship at 8:00am, they won't even be finished with disembarkation from the previous sailing at that time. Then they have to clean the ship and get it stocked and ready for your sailing.
Don't ever try to be the first in line. The line is longest just before they open boarding. Be in the area but wait an hour or so after they begin check-in and the line will be a fraction of the size. Everyone trys to get there early, guess like you they're all anxious. Patience will save you a great deal of time standing in line.