Im new to this and feeling confused. I urgently need help with defoliation and a few other things.

I would need to see pics of the stems near the internodes to see if the plants on the “right” have began pre-flower or not . I also had a hard time telling exactly which 3 plants you mean . Last thing when it comes to defoliation. It’s a personal preference thing that’s different for everybody . Depending on what you want to accomplish and what you are most concerned with pertaining to plant health will lead you to your decision to defoliate or not too. If you want more light access to those buds forming , greater air flow , decreased potential for powdery mildew just to make a few reasons then I would say yes defoliation of the fan leaves is what you should do . If you feel that you have worked hard to grow those leaves & don’t want to even barely “stress” the plant at all whatsoever because you are afraid you’ll take too much then I’d say don’t defoliate . If I were you I’d dive right in and get some hands on learning experience . Watch a couple YT videos following someone you feel has the quality and yeild you are wanting to accomplish & imitate what they do until you’re comfortable and know what you are looking for . It’ll probably hurt your feelings for a while when you defoliate BUT she will reward and thank you for it if you decide to do it .

By the pictures and the white hairs I can tell for sure you have at least 4 plants that entered the flowering period, those 2 on the right side should follow very soon. You got nice plants in there no issues imo. Here I don't do defoliation on autos, I just tuck the big leaves down if they are blocking the light on a promising bud site.

Some are in flower already, seeds are all different, so its normal. Grow looks very nice. I personally would not trim anything for now, just i would tuck leaves under side shoots and expose all side branches to light. Its a daily training, but it helps to keep all possible plant energy and capacity for max growth. Have fun !

First one nitrogen toxicity, not that high but try to control it, i like to def just biggest one fans and whole bottom leaves which anyway dont get light to focus energy to higher parts

What's good, dawg? Good question and nice pics 👍. Defoliation is a tricky topic, especially for autoflowers. Some reasons you would want to defoliate. 1. Increase airflow to parts of the plant that need it. Humidity concerns etc. 2. Increase light exposure to lower budsites that aren't getting enough light. 3. Increase quality and density of the top budsites through defoliating lower budsites (lollipopping/pruning) 4. Increase quality of and density of budsites by removing foliage that doesn't support the production of buds (?contentious?) Personally, I prefer to not defoliate my autoflowers at all unless it is necessary to avoid major issues like mold. There seems to be differing opinions about this with many of the opinions holders (myself included) not actually being well versed in the actual science of it, so definitely take what I have to say with a grain of salt and maybe get some second opinions. Here's my thought process: 1. Since autoflowers are notoriously susceptible to stress, I try to not stress them at all throughout their life cycle. Excess defoliation can cause this and reduce size and yields. 2. I can increase light exposure to lower budsites without defoliation by plant training (LST/HST). 3. Leaves store nutrients for later use. You run the risk of experiencing mid-late flower nutrient deficiencies due to the loss of so many leaves. (?contentious? Also mostly only applicable to organic growers who don't use a liquid nutrient feeding schedule.) If I were in your shoes, I would not defoliate. However its probably not a big deal if you're using synthetic nutrients and are on a schedule. Your plants look very healthy and happy and there would be no harm taking off a few leaves here and there. As for your three other plants I can't tell if they're flowering or not. You'll have to grab some of the branches and check for calyx formation and pistils. Odds are that they've just started preflower though. Its quite common to see many different phenotypes even in the same pack of seeds. Some flower later than others etc. There is a small chance you got wack genetics, but I wouldn't count on it especially if those seeds are from a reputable breeder. Hopes this help friend. You're looking real good 😎👍