Dick, pre-planning makes very little difference. The controller doesn't sit there waiting for you to call at the nominated time with a corridor of reserved airspace for you. You may or may not turn up after all. All it means is they have your details to hand a little quicker. Calling a few minutes earlier than required is always a good idea.
Last edited by le Pingouin; 1st Jun 2014 at 11:08.
Reason: Additional comment