you'll need to put cylinder one in TDC position to get the dizzy timing correct - its done statically when the engine is off.
jack up the drivers side front wheel, take the cam cover off (unclips on GTI's)
put in 3rd and turn the wheel until you get these marks aligned...

then the dizzy arm need to point to cylinder 1 position - from memory there is a mark on the plastic ring on the inside.
Put it back the cap on and refit cover, lower etc.
Done.