I did two B2B cruises from PC (one in November and one in late December). BOTH times it was a nightmare (I'd use a stronger word but not allowed here).
On the November cruise, there were 10 of us B2B. We met in the theater at 9:00 a.m. where we were told we had to wait for a zero count before they could deal with us. Around 10:30 we were finally escorted off the ship into the terminal where we had to wait in another area to go through immigration then just...waited. Our escort's radio didn't work so he had to keep running outside to find out when we could reboard. Finally around 11:30 we were brought upstairs to reboard only to see that general boarding had already begun. 😡
On my December cruise, I was the only B2B passenger and went through essentially the same process although I was told by the concierge it would be a smoother process "this time". It wasn't and a lot had to do with the PC personnel who were rude and downright nasty stopping us constantly along the way demanding to know what we were doing. When I was finally taken down to immigration, I and my escort were the only two non-employee people there. I asked a worker if I could just go through and she screamed at me that I would go when she said I could go. Literally 10 seconds later she announced dramatically that I could go. Then suddenly I was told to "wait here" until she said I could go back upstairs (again less than a minute later I was "released"). Once again general boarding had already begun and to say I was angry and frustrated is an understatement.
I spoke with the GM once I was back on board and he had heard many similar stories before and said they were looking into the process.
Port Canaveral is the only port where I have had such experiences. In other ports, you're off then back on quickly and get to enjoy the ship for some quiet time before boarding begins. I truly hope things have gotten better and you will report your own experience back here. Bon voyage.