Starting Nutrients

I have the full spread of fox farm nutrients and I have my plants in fox farm happy frog soil. When does everyone usually start their nutrient regimen? Worried if I start too early I’ll end up killing them. Currently 2 week old seedlings growing their second set of true leaves. Only been watering with PH’d water so far.

I’m also planning on halving the suggested nutrient amounts.

It matters how much soil you have vs plant size.
When your roots fill the first smaller container you can pot up or start to feed.