Depends on you soil, a light mix i would go 2 weeks then formulex, though ionic say you can use it earlier - i did not buy my nutes till some time into my grow then i used formulex, mainly as a foliar feed, then at 4 weeks i would go soil nutes 1/4 strength and still foliar feed with formulex and slowly increase dosage. For a full soil ( not really recommended for young seedlings) you would have to lower your nuts and/or delay them more, but as i have not grown in full soil i cannot be of much help there.
none of these suggestions are written in stone, each plant/strain is different. A good rule of thumb is to start out with no nutes then very gradually introduce them a deficiency can be easlily rectified, an overdose can be more damaging and once the harm is don you cannot resurrect damaged areas, you can only do an emergency flush and hope to save the main body
none of these suggestions are written in stone, each plant/strain is different. A good rule of thumb is to start out with no nutes then very gradually introduce them a deficiency can be easlily rectified, an overdose can be more damaging and once the harm is don you cannot resurrect damaged areas, you can only do an emergency flush and hope to save the main body