What is done is done and it is good to experiment to find out what works best for that particular strain. I personally avoid topping autos based on the research that I've done and by experience, I don't want to stunt the plant's growth at the early stages. Although you can get good results from topping, but I believe the plant would need to be happy and healthy and keep in mind it will take longer to harvest as they have to recuperate from the stress. I think your best bet with autos is to LST early and defoliate when you are out of pre-flower. Best of luck!