Flowering is based on how big a plant you can grow... a plant will x2 or x3 in size during flowering so once the plant is 1/3rd the size you can fit in your grow space throw it into flowering. also make sure you have enough light to support that size plant... if your going budget on lights start flowering much earlier.. the problem with your plant could def be due to the light gettting at the rootball ...... not good!!!!!!!!!!!!!!! this stunts growth also could be from nutes in soil... anyway in order to prep rockwools or those lil peat pucks get a tub/basin of ph'd water between 5.5 and 6.8 and soak em until they swelll fully up... then stick ur cuttings in ... I have never done clones this way. but i heard youll get around 50% success rate using rooting powder from any garden center and these rockwools or Jiffy pucks also will take 10+ days to show roots....... I just built a bubble cloner for $55 bux including areoponic root stimulating solution...... just put my cuttings in yesterday... supposed to show roots withing 14days more like 5-9 days thow also is said to have a much higher success rate .. more like 95%.
Also take cuttings from the lower branches but any will do fine.. make sure there is atleast a good sized top to each cutting .. Just look at the branches of ur plant and imagine which branches if removed and kept growing would end up being a nice plant... thats what i have done!!!!!!!!!!! will be updating grow journals and post on bubble cloner in near future... Ive got 11 nothern lights seed germing now, 10 clones on the go+ their mom is still has alot of nice bud sites so i think im gonna flower her out and keep that strain goin with whatever of the 10 clones take.. then will be planting the northern lights within a week... prob gonna cross the northern lights with the skunk indica bagseed clones... could be promising.!!!