Nute strength and height of lights

In what week would people from this forum recomend to start using full strength nutes? It will be my 3rd week of grow on the Tuesday 3rd of april.

Also what height do i keep my 4 x 600w HPS lights away from the girls. some1 told me as a rule of thumb: from your fingers tips to your elbow.
Is this a rough but good guide to follow?

Flourescents: proximimty
400w HPS: 1 foot
600w HPS: 1.5 foot
1000w HPS: 2 foot

I don't add nutes until the first month. Then start at 1/4 recommended strength.

Thanks Mogie that was quick!
Do you use any addatives at all with in the first month? Like superthrive, formula 1, nitorzym?

I add a little superthrive but that is it. But that only after the first two weeks.