Best time to do is whenever the barks start to slip. The thousand calories of your bacon are still no match for the Reed avocadoes which have the highest oil content of them all. But don't worry those are very good HDL enhancing calories, entirely good for your heart.

Well as long as maximum air temperature is within 60 to 90 deg F and that the minimum stays above 45 deg F, it is always a good time to cleft graft or bark graft. You don't even need the barks to be slipping if you do the cleft graft. But with bark graft, barks should be slipping. When cleft-grafting, do it on the terminal ends, near where the wood is firm but still green.

To enhance take, it requires tremendous preparation which pays off with higher success rates. When collecting budwoods, ten days before, cut off the leaves of the terminal ends of the scionwood, leaving the petioles. This will make it look like you have porcupines. Then after ten days or whenever the petioles of the scionwood starts to fall off at the slightest touch (whichever comes first, the falling off or the ten days), collect the scionwood and cleft graft pronto!