Following the chin up in the bow is fine but don’t do it aft
I’m sure your aware (and probably have already done this)To attain the proper water line you need to load the boat as you would for use (including full fuel and water etc etc) and put it in the water. Either let it set in the water for some time to mark it naturally (scum line) or mark it with some thing like a grease pencil.
Every boat sits different in the water when loaded. This is an example why not to follow the chin all the way aft. Nothing worse than spending time on a boot only to find out its below or not parallel to the waters surface (the sweep up to the bow is fine)