On the 12-4 Magic cruise, I had already decided on what night I wanted to have dinner. When I got to the entrance of Rockin' Bar D, I looked at the board that was set up, listing the dates and times still available. The night I wanted was still available, so I looked for the station that had Tuesday night, I went to that station, there was no one in front of me, and booked our dinner.
I then asked where the brunch reservations were being taken and was told that PJ, the manager, was taking them at one of the booths. I walked over
and spoke with PJ, a dear, sweet friend CM, we have cruised with many times,
I took his suggestion of "Sunday brunch", we chatted for a few minutes and
I was out of there in about 10 minutes, 15 minutes tops.
So, in answer to your question, there are what I call "stations" set up for guests to go to and book the reservations. There were "stations" for dinner, and brunch. I'd guess that PJ was also booking High Tea, but since we weren't interested in HT, I didn't think to ask.
If you go to the reservation site as soon as you board the ship, you should not have any problem booking a dinner and brunch.
Phyllis