My mom always filled the sink with hot, boiled water on one side, and ice water on the other. She would dip the peaches in the hot, then move them to the cold before taking them out. You will know how long to leave them in the hot water when the skins are loose. You are just trying to release the skins, not cook the peaches at this point.
My MIL uses a method that I find easier (shhh....don't tell my mom
). You find a deep dish electric pan, and fill it about half way with water and bring to a slow steady boil. Put the peaches in and fill the pan. Flip the peaches after a few minutes, then remove them to cool on a plate. This method works well for many hands because you can set up an assembly line: Blanche, cool, remove skins, slice into jars.... I set up in a row on my island using this method, even when I'm working alone.