First Time Grower - Am I ready to switch?

Hi ppl,
This is my first grow. planted seeds 10th august. They sprouted following day! (No idea what strains, were given to me, but smells slightly of cat piss lol)
The plant on the left is going well, I'm thinking I can start flowering now? Is it a sativa cos its taller than the others.
The other one you see got yellow leaves and crispy a couple weeks ago, it has recovered now. I put some vinegar and epsom salts in and it came good.
I'm growing on a nft system, with 600w (cfl? the one the shop gave me for veg)
Part a and part b nutes, cant remember brand.
there are 3 other plants here smaller than the first plant, one wasnt good from the start went totally yellow, but its growing like hell now. I think my ph was too high, cos lowering it, and I have 2 " growth a day, so really these plants have only been doing so well since I did these things, prob 4 weeks of great growth..Thats when I bought the light kit too, had them under some ufo led's.not enough light tho so bought a kit.


I briefly flowered and determined the left plant is female, so took clones yesterday. I pulled out 3 males (I suspect anyway). they didnt look like the same on the one I have here. Its on a no nutrient water at the moment. Thinking this is good before switching? this is second day.
Whats a good flowering nute?
Thanks all.

loads good nutes, advanced nutrients, plant magic etc. As for flowering theyl double in height that sativa could tripple so how much height do u have to play with. u have some yellowing leaves and tip burn on a few of them, i suggest half ur dosage of current nutes and build up again, do u feed then water feed then water, like a cycle? cause constant feeding isnt good for them. anyways other than that looking good, sort the problems before flowering.

Thanks for that
Yeah theyre not yellowing nor tip burnt now, thats a couple weeks ago. New growth is perfect. Yeah might be in trouble with the sativa's height, but I'll work it out. I didnt top that one and didnt think about it tripling in height. oops! Yesterday I noticed still have some leaf curl, is that too much heat does it, they curl lengthways kinda twisting.