first grow, first nutrient feeding help

so im doing my first grow in coco about 50/50 coco perlite and im wondering when i should start giving them nutrients? so far its been only ro water phd to 5.8-6.0.

i have regular, feminized and auto flowers (the autos are about 10 daays behind the others) all growing at once, from what ive gathered you shouldnt start nutrients for about 3 weeks or 3-5 nodes but my plants are growing like crap, very light light green leaves, very purple even on the veins of the leaves of some of the plants, which only have 2 sets of leaves on the most advanced.
one of the ones with only 1 set of leaves is showing some of the worst purpling, should i have been giving them light nutrient feedings sooner?
as of writing this ive giving two of the "runts" with heavy signs of purpling a light nutrient feeding of 150 ppm just to see what happens as i suspect growing in coco with no nutrients is the problem and i shoudl have been giving very light feedings the entire time, thank you for any repleis / input people can give

another question would be what PPM value is 100% safe for a plant at aany stage and what PPM value would be just to low and just wasting nutrients (my ro water is about 6 ppm)

...yeah, pictures would really help bro but it sounds like they are hungry.

...and lower your ph, coco likes the ph between 5.2 and 5.8.

peace, bozo

Ramp up from seed. Ramp down before harvest. Its like any other lifeform. Needs food thoughout just depends on how much.

Try to learn ec vs ppm when asking for help. Fact is you saw the suffering and knew something was wrong.

Ramp up nutes till the leaves r green and vibrant. Dont forget to add calmag since your in coco.

ok thank you for the reply guys, got my nutes+calmag mixed up at 1/4th strength (150ppm) and phd to 5.2, when they wake up in a few hours ill water them and see how it goes

seems one big mistake i was making is when i flushed my coco, i used regular RO water (around 7 ph) not water phd to 5.8

also i wasnt checking my run off water PH, two things i will start doing

With coco, the medium is generally inert and contains no nutrition. So seedlings pretty much need some sort of nutrition once they pop out of the medium, not waiting until multiple nodes are formed. As said, for seedlings you will want to do something around half strength feeding, then slowly ramp up as it grows.