All the cardinals congratulate him as well apparently. There was a video from the vatican press office showing this and also showing him briefly praying in the Pauline chapel before going to get changed.
There was also a document that had to be signed with his papal name on.
I also wonder when they write their first speech and tried to google this unsuccessfully. They must prepare something just in case they are elected once they see that they and perhaps one other person are moving ahead in the votes. Otherwise how would they have time between the white smoke going up (which apparently goes up as soon as the vote is completed and the new pope has accepted the position) and appearing on the balcony to write their speech?
Also do we think every cardinal already knows what their papal name would be if they were ever to be elected pope? They must have thought about that in advance too. Otherwise they'd have a panic on, oops, I've been elected pope, need to be on the balcony in less than an hour and don't know what name to take, oh, I know I'll be Gregory (or whoever). And yet there's always an explanation by the pope later as to why he chose the name he did.