Out of habit, I use two water rinses after the developer for film and a two percent acetic acid stop bath for paper. This has worked fine for more years than I can remember. Logically, it may be backward. After all, film development is what needs to be really stopped at a definite point - paper essentially gets developed to completion. An acid stop bath may give a little insurance against stain on the paper, and it may protect the (very slightly) acid fixer, but not much. In any case, it seems to work. This is not an area of great criticality unless something doesn't work. If that happens, you need to start again with the conventional methods.