when should i give my plants nutrients

I heard people say that I should wait until the second week to start giving my babies nutrients.
this is my first grow ... my babies are 4 days old since they sprouted .. they look good
growing medium: pro mix
nutrients : General Hydroponics Flora Series (Gro, Bloom & Micro)
Strains: purple haze, blue lemon thai, white widow
Light: t8 flourescent

when should I started feeding them nutrients?
should I give them the full dose, half does, etc.?
Is them other ways I can feed them (supplements) this early?
and if so which kind of supplements?

When thy ask for them.

Try waiting till week three to play it safe. If you want to start earlier try it with one and have at least two more plants growing as a backup.

start at 2 weeks 1/4 stregth then work your way up

start feeding them when they have rooted. usually when they have grown 2-3 sets of new leaves. should start with veg nutes measured to 300ppm. the only additives you might add are root boosters but you don't need them really.