The min shir I have heard from my rav is at the bone. There is a bone right by your ear canal the peyios have go a little beyond that. Also a 3 or 2 is the thickness of the hair by the payios I agree they should be a 3 maybe even a 4, but I have never asked my rav how tick they should be by the bone, but he did tell me that is the point where they must grow.
In flatbush their are a few barber shops that have a sign explaining the halachos of peyios that you can look that if you do not have a local orthodox rabbi to ask this question to.