When to start using fertz?

I am wondering when it is safe to start using fertz on my plant. It is about 2 weeks old now. I have earth juice fertilizer and can't seem to find where it says to start using it with your plants

When your plants tell you. About 2-3 weeks is when i start to feed nutes. Learn to read your plants and that will go a long way.

Going from seeds let it ride in the soil with correect ph balance water... Add half strength ferts in after about 4 weeks.