|As long as the marks are lined up most importantly the cam marks and crank mark lines up to the timing belt marks should be fine.
Count belt teeth as well if you like and turn engine over a couple times before firing. Replace tensioner while in there, use a vise to compress back if you need do not use screw as it will snap.
If the engine is being newly put together it's important that it is at compression or exhaust stroke, you dont want to do the timing belt and have it 180* degrees out.
If the engine was already running while doing this you should be fun.