Nutes for the Newb!

When do I start watering in my food?

And do I follow the instructions or is this outside of the "all purpose" catagory?

I would start about when the first 5 bladed leaves start forming. (just my opinion)

And start with 1 quarter strength and slowly move up. I end up with double the instructions amount at about the 6th week of flower, then stay there till the end as some strains can take that amount of nutes and some can not. Research your strain.