Only grown autos before which i know are light fee...

You can wait some weeks with feeding. The only nutrients you need is cal/mg because you grow in coco. But be carful at this stage and sie only a small dosage 👍 And root boosters are a really good at this stage 👌 If you plan a 7 weeks veg with 9l pots i would recommend to start with feeding (veg nutrients) in week 4 or earlier if they show signs of deficit. Start with a low dosage of veg nuts, i believe you will use the canna line? Which is a non organic nuts and with non organic nuts is less more.✌️to much will lead to a salt deposit (high ppm of the soil) which will damage your roots/ the hole plant and kill a good microorganisms (thats why i would recommend organic nuts 👍 with organic nuts its nearly impossible to overfeed the plant, the hole plants are healthier and the buds have a better quality/taste. Some people say you will have a lower yield with organic nuts, but in my experience its not true if you do it right 👌 Best wishes and good luck 😎✌️