At 10:30, *if* the lines for security are low you *might* be allowed to go through and wait with everyone else getting on at the 10:30 time slot. most people with a 10-10:30 time are waiting in chairs until the ship gives the go ahead .
NJ port is pretty strict about arrival times, but worst case you can always wait on a bench, or give your bags to the porters and explore Harbor View Park, see the 9/11 Teardrop monument etc - it's on the other side of the parking lot