When growing indoor with soil how often should i add nutrients to the water

I have a few plants in like the 3 week stage and i just purchased B.C grow and bloom kit. Now since im using soil do i water the plants with the nutrients every watering or do i space it out or should i not be adding nutrients this early or at ALL?

At three weeks old you should be adding nutesevery time you water. Start at 1/4 strength and bump it up over the next two weeks to full strength. VV

I add nutes every 3rd water at 1/2 recommended strength. This was per recommendation of my hydroponic coach