Hi mate,
You probably know that sog works best using cuttings from a selected mother, though you can get away with seedlings, you will always have some difference in height and general appearance and finishing time ect, making it difficult to get an even canopy of main buds.
But because you are growing from seed this time, I reckon you need to be looking for a good all-round mother plant as a keeper from your pack of DDHS.
Grow the whole pack out in one go if you can, bear in mind you will have at least 40% males to chuck out, so you should have enough room to veg them for 5-8 weeks as you still need them to be mature enough before flowering unlike cuttings that come from an already mature plant.
Take a couple of cuttings from each plant before you go 12/12, label & root them in a propagator under some florescence lights, bin male cuttings when you know the sex from your mature plants . Keep the female clones just ticking over in permanent veg under flos. That way you have a copy of each of your DDHS ladies to keep as a possible mother, and just bin the ones that are not to your satisfaction after you have finished flowering out the originals. And try and make a decision on one or two phenotypes as keepers.
I wouldn’t prune the main tops as you are looking for good central bud growth when growing sog and so you want to choose a plant that has the best looking main cola from all the female plants you have, just take off the lower branches that receive little light as the plants grow.
There’s many things to look for in a good mother plant for sog, you want ones that have a high flower to leaf ratio with a good main stem, not to much side branching, reasonable finishing times, mold resistance, no hermi traits, and of course a high that you enjoy as well as taste and smell. Once you have your mother plant, growing sog will become much easier as clones will be identical in height and shape allowing you to pack many more in the space you have.
That’s touching on the basics of how I do it, hope that was the sort of info you were after and not just going over old ground.
Good luck with SOG, get it right and you wont look back!
All the best, Bud Brother.