I strongly reccommend to set all pulley markings, as it is really easy to move just one of four, espiecially when doing it for the first time.
I'd second that; the markings are there for a good reason so use them. It's true that you can set your own markings anywhere and as long as nothing moves you'll be fine but might as well use all the markings that are there for you. Number 4 cylinder should be at TDC and there's a mark on the crankshaft pulley for this. And don't forget to order a new set of knuckles for you as you're bound to loose some

(or have lots of plasters handy

) I always scrape off quite a few of my knuckles when changing the belt on my Trevi
