i would think that starting a mother and taking clones off that is the best method for sog or a purpetural sog.

usually it takes anywhere from7-14 days for the cuttings to grow roots, you can either go with a bubble/aero cloner or use rapid rooters or rockwool

i have personally tried bubble and rapid for my cloning and prefer rapid rooters cause im always afraid of hurting the roots when transplanting into the soil.

you can put fresh clones straight into flower if they have a strong root system but i would prefer atleast 1-2 + weeks in veg before you flower