I wouldn't base it on this year as this year was a disaster with systems down and changes in testing and basically anything that could go wrong, did go wrong.
But...they had everyone doing B2B meet in Fathoms at about 9 (I think). They kept us there, walked us out as a group, had our passports stamped in Barcelona (the only time they were stamped). We bypassed the testing line because we had a 90 day exemption, so we just waited...and waited...and waited some more.
We were back on board before around noon, I think, but from what I heard, that's NOT the norm and it's normally much earlier. I think the goal is to have B2B's back on board by the time people start showing up for their PAT's and that did NOT happen this year.
They will check to make sure you have your passports/key to the world cards, several times. And there will be people who still don't have them. We got a letter in our stateroom a day or two in advance to tell us the process.