The 1.8 can be difficult to get spot on. I've just done one and had to rotate the bottom pulley slightly before fitting the belt as it does move back when under tension. It's not ok to leave as it is. It won t run properly. I suggest you watch a couple of YouTube videos so you get the idea. Also double check you have the right belt. VAG changed the belt and pulley set up on older 1.8 engines due to tensioner failure. The one I recently did still had the old belt set up and I had been given the newer belt. Luckily, I noticed before fitting.