Starting out from seed in jiffies bc thats what worked for me so far.
Decided against using rockwool because I like the reusability of clay pebbles. Designed some 3d printed netpots the size of 7.5x7.5 rockwool cubes for that.
Had to pull them out of the jiffy to make them root in a temporary dwc.
After four days, first roots started to show at the bottom.
Its fine, they will airprune and die off.
I would make sure tho, that the tank itself is clean and cannot infect the roots with anything, also the tank needs to drain properly.