Hey there 👋
Normally I’d suggest moving your germinate seed direct to its final pot, as auto flowers have pre determined life cycles and don’t handle stress all that well. That being said, I’d recommend moving the over sooner then later, the smaller root systems will be less likely to be damaged.
I personally have been using fox farm soils. Either the ocean forest, or happy frog. My local garden center sells them both, as does most hydro stores.
Happy Growing 🌱