Should I flush or feed?

I'll post some information on what I'm working with so you get a better understanding of my situation and hopefully It'll help you answer my question,
"200w CFL blue
JI-2 soil
Water from tap ph around 6.5-6.7ish run off is around 6.3
temps are around 26ish with lights 20c without
Strain is S.A.S (Super automatic sativa)

Right now to my problem... so my plants are around I'd say 1 month old give or take a few days (lost track >_>) I've fed them once with Bio-grow and I think they developed some nutrient burn.After seeing some signs of browning I figured I'd stay away from the nutrients for now and just give them water until they start to yellow and they'll get better.
Here are some pictures of what the leaves look like now (the ones I'm concerned about)




That's the first plant I'm a bit confused on the matter, they're showing yellowing which I read that's nutrient deficiency then I see some browning and crispy leaves which could indicate nutrient burn, not sure whether I should flush or feed.




That's plant number 2.



Thank you for taking the time to read my post, hopefully someone can help me out.

Feed ..... just stay within the guide lines on the nute. label

Those original bottom leaves are gonna fade away. Stay on a feeding/watering regime and do 1/4 recommended dosage and if she likes it, bump it up slightly. Read up on the breeders recommendations (if any) and google the strain and read the different reviews.

flush then give a mild solution....