Just a quick question... why do you have to wait for the glowplug lights to go off before starting the JTD, and what potential damage are you doing if you don't wait?

they wont be warm, no harm if car starts i dont think, but often in the winter if you dont wait car wont start

Glow plugs are not like spark plugs in the sense they create a spark. They are used to create heat in a diesel engine. To understand why there is a need for a glow plug you need to understand the workings of a diesel engine.
http://www.2carpros.com/articles/how-a-glow-plug-works

you can start it before the plugs light go out, but you run the risk of building up excess cr@p in your system. Diesel needs to be heated to burn correctly in the system if its not heated then less of the fuel is burnt and more soot comes out of your exhaust (thats laymans terms anyways).
i dont see a issue with waiting for the few seconds - the car then has the chance to run though all the checks as well
roy

never have waited never will wait had my car since new and it's always been fine, i always forget when i get in an old style diesel and you have to wait for the silly light to go out drove mates 306 and it felt prehistoric.