I’d recommend begin in the smaller rockwool cube 1.5/2” until that cube is encircled with white healthy roots to the view that u can barely/not see the rockwool, then place that cube into the next small block maybe 4x4” veg for 2/4weeks then place that cube onto the slab and rock it out that of course if you are growing for big flowerplants . You will not be disappointed use LST with scrogging net with a 1” then second tier 2” third tier could go to 4” i stay with the 2” and take advantage of every square in that trellis. Patience, training, nurturing nutes with added enzymes and supplements to get a = heavy brixx. How’s 2-6gram knuggz sound?-better yet visualize that as you look across the canopy at 2’colas or more, of topps. I highly recommend HarleySmith, Prof. a veteran in the hydroponics and cannabis industry, with over 25years’ experience as a hydroponics consultant and research scientist. , and Bruce Bigbee Phd,an American scientist, his work includes research into space farming with NASA and at Utah State University, where he is the Director of the Crop Physiology Laboratory. Jeff Lowefels “teaming with nutrients”/microbes/fungi/bacteria. These men will change your life!