Do what the cam manufacturer tells you don't follow the herd!
#1 piston at TDC and dots together! cant go wrong here now the reason they put them at 12 is for a fast fire up but its going to move when you spin the engine to set your valve train. So just line up the dots and leave it at that. plus its easier to use a strait edge this way to check to make sure they are inline with the crank and cam