If you are not taking Disney transportation from a Disney resort (or from the Hyatt at the Orlando airport) you will need to select a Port Arrival Time before your cruise. When you select the PAT, you will also be assigned a boarding group number. When boarding opens, groups are called to board in order by boarding number.
If you are taking
DCL transportation from a resort or the Hyatt, you will be automatically assigned a PAT and boarding group based on the bus schedule. That may be earlier that what you could have selected yourself, but it could also be later, depending on how buses are scheduled from each resort. If you are using DCL transportation, you will be able to enter the terminal as soon as your bus arrives (rather than having to wait outside for your PAT to arrive) but you may still have a wait inside before your boarding group is called.
With 4 kids, it will be easiest to take Disney transportation from Walt Disney World. However, since DCL transportation charges by the person, it may be less expensive to use a van service that charges by the van.
If you stay at a hotel in the Port Canaveral area, you may be able to take a hotel shuttle to the port. When I stayed at the Country Inn and Suites a year ago, there were a few shuttle buses running, and guests were called onto buses based on their Port Arrival Times so they wouldn't need to wait outside the terminal.
