Here are a few peaches from last summer’s approach grafting experiments. The initial graft looked much like the SMC_zone6 pics at the start of this thread. I let them grow for a month or so before removing from the scion donor tree and cutting the spare top off. Grafts were made at several different times in the summer, and most of last summer’s temperatures here stayed below 70 with some very cool stretches. Not very good pictures, but most of these scions are only 5-7" long with approximately 3" of actual graft length. The long one is about 14".
Note the fourth picture is of a dead graft. The graft looked good when I made the removal cuts, but got slammed by a sunny day a couple days later. The scion are vulnerable after the removal cuts as they have to figure out their new supply lines, and leaves want to droop. I believe a week or two of shade would be beneficial at this point.