How are defining a plant being Week 1 of Veg? Is it sets of leaves, time post germination or is there a method people prefer for indication?

i think those schedules are meant to be taken as week 1 without considering life stage. 500ppm of nutes won't stall or cause problems. I am in soilless, which is a bit different than soil if relevant, and feed at 650 elemental ppm from the get go. Haven't stalled or caused a toxicity in 6+ years, so far. Never seen a plant shocked from potting up either. A lot of stuff gets repeated ad nauseum. If the anecodote doesn't exist in general horticulure and only in the weed-growing hobby sub culture, probably not true. Even those more general and older anecdotes demand some scritiny as there is a whole bunch of marketing out there that takes advantage of people's neediness related to gardening hobby. If you are in soil, it completely depends on the soil you are using... some can feed a plant for a couple months and adding more to that context early on would be a bad idea. if you want precise answers and solutions, soilless/hydro is more for your personality.. soil is like riding a bike... lots of unknowns, lots of variance between products and requires familiarity to tie it all together.

try 350ppm for a week then we'll see ;)

I personally approach feeding with a "less is more" approach. I think it is easier to add more nutes than dial back, but that is me. I usually count "week 1" of veg as a few sets of leaves so this could be a week or longer since the sprout popped up. It depends on the strain and each plant. Your plant looks pretty early into the veg stage still. I think jumping into 500 ppm right now is too early and you might risk overfeeding the plant at this point. Ive done a few weeks of 200-300 ppm and then I usually ramp nutes up slowly to 500 after it's established more than this.

-A week ago there was Ca def, if the spot on the bottom fan will spread, then u,d up ur Ca fert -also i don,t like this purple petiole, what can indicate some more deficiency (N or could be also Mg)

Greetings ✋ Of course, growth will slow down. And this is already a little happening judging by the photo. But it's okay, I think everything will be fine. The transition to higher PPM values ​​must be done gradually. There is no need to give more now, the plant is now small and consumes about 300 PPM, if you pour 500+ PPM, then burns and other complications are possible. You also have weak lighting. I will drop options in light and feeding Based on the photo of the current growth Now feed 380-420 PPM and give light 12000-15000 LUX on the crown of plants After 7 days, feed 400-440 PPM and give light 14000-17000 LUX on the crown of plants After another 7 days, feed 440-480 PPM and give light 16000-18000 LUX on the crown of plants With such a smooth increase in both light and fertilizers, the plant will be balanced and correctly digesting everything that is in it. But do not rush with an increase in fertilizers. Because both light and fertilizers should go the same way to increase. Water 1 time in 2-3 days. Wait until the plant drains the pot, and then water to the drainage. Moisture must now be kept at a high level of 70%-80% Temperature on the crown of plants 26-28 Successful growth ✊