Hello ! I've heard that miracle grow is not a good soil for cannabis growing but I forgot why. Generally Autoflowering strain don't like to be transplant so many growers prefer to plants direct into the final pot because once the roots system have filled the pot they start to flower. So I would advise you to transplants once the roots have hit the bottom of your actual pot to the 5 gallon one to give the roots more space. And prefer the fox farm soil when transplanting! I hope it will help you 😁✌️🏼