You are met at the port, right where you get off your ship, by several of the buses, so no long queuing involved. Plenty more buses appear at regular intervals. We have done several of these tours in Europe and this is probably the longest one for the distance covered. In the morning we got off at the Vigeland Sculpture Park and spent over an hour and a half there without realizing it. No problem getting on another bus after a10 minute wait.