Is 8 oz of water about right for 3 weeks old plant...

The watering amount is very dependent on many factors mainly environmental and size of medium. Higher humidity and lower air temp will reduce the water from evaporating from the medium. And reduce water perspirated from the plant. Lowering your water consumption rate and lowering your frequency of watering. You should always give the medium a good full watering and allow it to dry before re watering. So larger containers will require less frequent waterings.... atleast at first. Lst can be started but remember training branches makes plants wider! You dont want your canopy too dense... and restrict your airflow... that's asking for problems like mold. But to answer your question your plants are quite big enough to start training. And for your last question on nutrients... vital minerals are required by plants to live a healthy life and live up to their true potential. An unhealthy plant will always produce less than if it was healthy... so nutrients are a vital thing regardless if u use around the house "organic" good or store bought made for plants goods. U should give them something. But to me it looks like ur plant suffered a over feeding of some kind because the tips of ur leaves are burnt... seemingly looking like nutrient burn. Have u feed the plants already? Hit me up if u have more questions or if u need more clarity! Happy growing and stay lit fam!

Hi! 1. to understand exactly how much water the plant needs-I recommend you to weigh the pot.first before watering, then after watering, then after a day. if you weigh every hour-you can calculate the exact water consumption of the plant. overwatering always bad for the plant 2. you can use LST method, but why? you have 4 plants in such a small area - they will be closely. 3.I began to use nutrients after 5-6 weeks, before that only water. If you're new, you'd better use water. The best time to use nutrients is - change the color of the leaves sorry for the bad English 4-20 Bro.👍