It should be just fine to transplant, i have learned that it does not hurt them at all. I did an open air transplant, complete with soil removal from the main root system. Plants never Stunted and produced well. Now im not saying that sowing to final pot is a bad idea, the less you mess with them the better but it can be done with care.
Now i will say this about FF soil, not really, from what i have seen, a good choice as the sole soil in the pot, use it at the bottom of the pot and then add a non ferted soil above it. Let the roots have 2 gals of a 3 gal pot before it hits the FF stuff. Now as far at the nutes dont be in a rush to use them, you will see what you saw every time. We all want big producing plants, and pushing the limits is ok, but with moderation. I dont switch to any type of bloom food until i have bud sets.
Plant looks great man and wish you well on the rest of the journey.