Bag Seed

3 weeks after because the promix contain enough nutrients for at least 3 weeks. Even after 3 week I would give nutrients only when needed by watching the plant leaves. Moreover it seems that the less powerful is the light and the longest the nutrients are lasting in the soil , it is due to a slower stimulation of the plant by the low light so she cannot achieves the same photosynthesis than under more watts so she’s using less nuts

You can't have deficiencies with your soil mix, only if the deficiency is due to another issue like an over watering. The N toxicity would have stunt the grow , you have a normal green colour , not to dark. Don't worry your mix is pretty enriched so no deficiencies will show up until 3 weeks and it's not a mix that is too hot so you should experiment no excess

Nutrient burn can also happen when plants or seedlings are grown directly in soil that has a high level of nutrients (a “hot” soil or growing medium) such as fresh compost, manure or a nutrient-amended soil mix. This usually happens to young seedlings, and they will “grow out of it” as they begin to use up all the nutrients in the soil, as long as more nutrients are not added. In general, plants use overall higher levels of nutrients as they get more light. Therefore plants in relatively low light conditions can get nutrient burn at lower levels of nutrient than the same plant would under bigger grow lights. Each cannabis plant is different, so you might have just one out of many plants get nutrient burn! That is completely normal. Sometimes you’ll also see nutrient burn leaf tips also curl or “claw”. The clawing can be caused by an overabundance of Nitrogen (Nitrogen Toxicity), which is common for plants that are experiencing nutrient burn from overall high levels of nutrients. Notice the tips of your marijuana leaves showing the first signs of nutrient burn by turning yellow, tan, gold or brown. A light case of nutrient burn will only affect the tips of your leaves. The yellow tips will eventually turn rusty brown and crispy. If you do not correct the problem, you may also notice the burn slowly spreading from the tips to the whole leaf. I have heard some growers say that a little nutrient burn is actually a good thing, because it means that you are giving your plant the highest level of nutrients it can use. A lot of growers have the mistaken idea that nutrients are somehow “food” for your cannabis plants, and so more food = more energy = bigger yields. This is wrong, instead nutrients are more like a multi-vitamin for your plant. Just like you can’t give a child 10 multivitamins a day to make them grow faster, you can’t give your plants 10x the regular does of nutrients and expect anything good to happen. The real “food” for your plant is light. Your plant produces energy from light through a process known as photosynthesis, which is most effective when the plant has healthy green leaves.

open image, then "copy image location", paste that into new tab and you can really zoom in. Can more easily inspect Awesome picture quality, @ChuckyK