There are many schools of thought on the warm up issue. Some people like to warm their engine up till the temp gauge rises, and then drive off, ensuing their engine is protected.
HOWEVER, you also must remember that the diff and gearbox oil are NOT at optimum operating temp from cold, and even though your engine is warm, doing burnouts etc with cold gearbox / diff is a recipe for a large bang - trust me, i've blown up a number of diffs in my time, a couple backing out and squirting it too hard (not a skyline though).
So, while i think it is important to warm up a bit before driving off (say 2 mins), you should really take it easy for the first 5-10 mins of driving time (under 3000rpm) to make sure diff and gearbox are happy too.
my 2c