I believe that planting an auto directly into the final pot is the preferred method as then there’s no transplant shock which autos, with such a definite lifetime, do not like, so it’s said to always plant an auto straight into the final pot.
Others don’t and have success, maybe it has to do with something about WHEN you transplant into the final pot as if it’s “beyond a certain age” the shock then becomes more apparent, I dunno. I always go straight to final pots no matter what I grow, and since I’m still learning I’m keeping them small with 1 gallon pots.
The plant you see below is an auto, pic taken yesterday, she’s around 8", 20cm, high and 18", 45cm, wide at, today, 21 days old. I’m expecting maybe a little over triple the height by the time she’s finished provided I don’t kill her. I succeed, I up the pot size. She looks happy enough at going straight into that pot and compost mix without any fancy rooting stuff or rockwool, or propagators or even humidity domes, straight in and as long as the dirt is good and you are careful with temps and watering any plant should be happy going straight into it’s final pot.
As elheffe says, you’ll see slow growth at first as roots go down and then an explosion in size, that little thing was clearing an inch in width for less than half an inch in height per day and that’s on what most say is a less-than-ideal 12/12 cycle (forced into it due to other bush) when she truly fired off, that’s when you REALLY have to watch the watering as it gets to easy to think she needs more than what she does, as you likely will from the start so be careful, and kill her just when you see the buds really start to fatten up. As I know only too well.