Nutes

I transplanted to new pots / soil about 5 days before putting em' into flower and its now day 8 of flowering. My question is, when should i start adding nutes?? I know the Fox Farms soil is supposed to have enough nutes for a few weeks but should I stat adding more phosphorus now?? I don't wanna nute burn em' but I'm also tryin to get quality shit...
 
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