I don't have much experience with growing these other then a few failed attempts at trying to grow one from a store bought avocado which finally succeeded after rigorous bleeching in order to cut back molds. To me this looks like major transplant shock though and less to do with what you are growing and more so the techniques applied. I could be wrong here but that stake seems to have been jammed into the ground after the transplant into the root system causing major drooping. Also could be a graft in which the cloning process might need some work. Did you start with a root ball? Chucks more in your zone, temps could be a thing too.