I opened timing belt cover to check how the belt is doing and found that the tensioner's arrow is not on the mark and goes slightly over.

Anyone with experience with these knows if it makes much of a difference?

You don't say what engine your car is. How many miles has the car covered? When was the car last serviced and did they change the belt? Is it under warranty still? Did you follow the exact procedure for timing mark alignment as laid down in the VAG workshop manual? I'm guessing it's the petrol 1.2TSI. If so, this engine has varaible valve timing which under some circumstances can affect the alignment, but I doubt that is a factor here. Is the car running ok at the moment? If so, you have pretty much answered your own question. As the belt wears and stretches the tensioner pointer can go slightly past the marker. If within it's normal working life, it should not affect the performance.  Looking at your belt it does look a bit worn but it is hard to tell from a photo and you can never go by the 'looks' of a belt anyway. A perfectly good looking belt can be well past it's change date and also be a breakage waiting to happen. As much wear to the belt happens inside the fabric of the belt as it does to the outside visible surfaces. 

Edited 4 September, 20187 yr by Estate Man

Yes, it's 1.2 TSI with 7000miles on the clock and 1.5 years old so the belt has never been touched. Engine is running fine. I was just wondering why that pointer is not on the notch. If you say it's normal then there is nothing to worry about. Thanks.

Ok Paul, yes...you shouldn't need to worry about the apparent misalignment. If you checked it again as per vag instructions after a run I bet it lines up perfectly. It's best to use a VAG alignment kit to make sure you have the crankshaft in the no 1 cylinder TDC position and that it's locked. If you haven't done that it probably accounts for the apparent misalignment. I'm not a VAG trained technician (I'm Honda/Nissan) but it's normally fairly straightforward to do this as you probably know.