Persimmon are easy to graft as long as the rootstock is vigorous. Here Was: Hello all, plus pics; now: bamboo discussions - #2 by JesseS is a link to my first post, scroll down to post 4. I was impatient and wanted to graft when the bark wasn’t slipping so I used a cleft graft. The wrap job was sloppy, but it is all I had on hand. I left half of the foliage on this male after doing 10 simple cleft grafts, which all took. These were all hybrid scions that put on 7ish feet of growth. This past weekend I bark grafted some kakis onto those hybrids. Plus, I grafted more hybrids and Americans onto the new male growth.
For weaker rootstocks I would wait until the tree is actively growing.