I have successfully grafted scion
wood which was at 1/4" green. I wrapped the whole thing from just below the graft out to the tip of the scion with Parafilm to stop it from drying out, which is what kills the buds on the scion. An alternative is to do a chip bud, using buds from the scion wood. Again, as long as you seal the bud thoroughly, there is a good likelihood that your bud will heal in and grow. (Here, too, I am a fan of Parafilm, which is soft
enough that the bud will grow through it