I would reccomend waiting because the plant loses a lot of energy when you cut the whole top off to graft. I grafted some persimmon rootstocks the first year I planted them and many died. The few that lived didn’t grow much, and a few of those didn’t make it through the winter. The established rootstocks that I grafted in early May after frost danger was past did amazing and they have grown like CRAZY. Many of them are taller then I am, with multiple trunks. I chip budded a few this summer, as an experiment, but I doubt they are going to do as well, or grow as fast as they would have if I had just waited until next year and dormant grafted.
I used a cleft graft on all of them, and had a very good take rate. (Not counting what I grafted too early that went through a hard frost… many of those died)