Hey Mate,
I have very good experience with the light mixes and Autoflowers.
ATM I´m using Plagrons Light-Mix, which has , like BioBizz Light Mix, a small mineral pre-fertilization.
Heavy Mixes Like BB All-Mix, or Plagrons Royal-/Bat-Mix. or Gold Labels Special-Mix are not ideal to start Autos, imho.
Too much juice for such young ladies.
I have my Orange Sherbert in Royal Mix, but put around 3l of seedling and cuttling soil in the middle of the pot where I plant the seedling.
So the plant has time to develop a decent root system, before it gets hit with a heavy dose of nutrients.
Hope this helps a bit, good luck and happy trails for the rest of the way!
Servus,
OimRausch