No, it will all move a wee bit as you tension the belt. You have to fight it.... The issue with locking the cam, and ip is that as you found the crank moves.
What I did, was to get all the slack in the belt at the tensioner, so that the belt was holding the others in, I think I even moved the crank a wee bit to compensate for the travel. So that as I tightened the belt the crank moved back to 0.
Once you get it, then you still need to rotate the engine by hand about 4 times to check for binds, then recheck the timing..... I painted a mark on the pulley so that I could get it close as I was rotating the crank before getting off the floor to check the tranny.