I'm planning fruit trees I can't afford to buy yet, so this tip is timely for me!
I'll utilize the cool days for the holes.
Also when I give little tours to my friends, I'll be better able to help them visualize with me where the trees will go.
Not needing to mow, I think I'll leave the holes empty though.
I can "claw" in some better-than-clay material as I wait.