For hanging, the back of the neck. For strangulation, the knot goes at the front. You wouldn't want the knot in front, as it could block your trachea, which is not what you want (very uncomfortable death). You want to constrict your arterie(s), not your windpipe. I'm sure someone will chime in and tell you something different. Anyway, read more about hanging in general here:
https://archive.ashspace.org/ash.xanthia.com/suspension.html
I'm not even sure how someone could do partial with the knot at the front. What would they do, lean backwards? What I've told you is how I understand the best practice to be based on everything I've read. Also, my cousin died by partial, and although not all details were divulged, it was clear that he tied a rope to a clothing rod in a closet, formed a ligature around his neck with the other end, braced his feet up against the back wall of the closet, and then simply leaned forward (knot at back of neck). I have no idea as to the type of rope he used, or whether he immobilized his hands, or not, behind his back.