Well, I'm no expert having only grown weed 5 or 6 times; however, I do have some experience with tomato plants which are not too far off from cannabis. And, experienced tomato gardeners do transplant their tomatoes at all different stages. In fact, I recently read of one gardener who ALWAYS does a series of transplants...she says her tomato plants develop a better root system by growing and being transplanted into successively larger pots...until finally being transplanted into the garden. Of coures these are not autos so not a perfect comparison.
I'm growing an Early Miss Auto in a 2-3 gallon pot, she's 25 days old and I'm going to transplant her into a bigger pot in a couple of days.
There will be some shock but according to the tomato grower, the shock is minor and the plant recovers quickly. I didn't want to transplant but I just don't think the 2-3 gallon pot is big enough to help the plant grow big. You'll hear many weed growers say never transplant autos but...Ima do it!
Autos are supposed to be planted in their final pot...no transplanting..from most everything I have read. However before I knew this I grew a couple of autos started in a 18 oz solo cup then to about 1/2 gal pot and finally to their final 2 1/2 gal pots and they grew fine. Maybe the yield would have been higher by not transplanting, I don't know. I started a couple of new autos this week and started them in their final pot so we shall see how much better this works.