once for 2 revs of the crank. So either way is correct: put crank at TDC (for compression or exhaust) and install belt with cams and crank in that position or rotate for 4 cam and 1 crank mar to line up.
Aware of need to count teeth. Good thought on the vise grips on the tensioner.
Is the manufacture date of the new Nissan belt stamped on the belt ? If not the belt could be on the shelf for a while?