I was taught that the C in transition should try to be in position to referee the "next pass" - or to be where he can officiate the player that will be getting that pass and the defender(s) who will be picking him up. So running down and setting up at the far end is a bad idea. Trailing the pack is a bad idea...find the happy medium. It will be different from game to game, and quite often from transition to transition within the same game. There is no "set" place to be...that's why officiating is an "art", not a "science".