Another thought....I'm sure the limo company is used to this...
You might want to call them from your cell phone when you finish breakfast.
The deal is that when the ship enters the port, it is no longer under the control of
DCL. US Customs and Immigration officially takes control of the ship, and DCL cannot open the big doors until it is "cleared." This involves all non-US citizens reporting to Immigration, luggage being sniffed by dogs, etc.
DCL ideally wants all guests off the ship by 9 am. Most of the time, this is a reality, but we were on one cruise when the big doors didn't open till nearly 10. DCL brought out the entertainment staff, etc. to keep us occupied, but it wasn't fun. Of course, when the doors opened, there was a huge line.
We usually do late dinner...thus, the later breakfast. Normally, we finish breakfast and walk right off the ship. No lines, no mess. Yes, there is commonly a line of early breakfast people waiting for the doors to open--we see this as we go into the dining room for our later breakfast. Again, DCL cannot control the opening of the doors. I'm sure they'd like to get us all off as soon as possible. They have a lot of work to get ready for the next group of guests.
Anyhow....a phone call to the limo company when you finish breakfast should have them at the terminal within 30 minutes or so....since they will already have an approximate time. And this should allow you to get off, go thru customs, etc. with no problem.