Continue giving veg formula 2-3 weeks after flip to 12/12 light schedule (during stretch). I'd run 1200ppm in the bloom tent.
It depends how far in & where they are at now? What I do is mix by their #'s which always end up less than they say. If it's close to my 1200 I'll add more *green (veg) or pink (bloom); depending on growth stage, to bring it up to my 1200 (or whatever # I'm aiming for; I run 1200-1400ppm, I wouldn't run that high in your shoes (yet), until you get a little more hydro experience and are comfortable with how they respond). *if you come in real low, use the 3-2-1 ratio; ie during veg use like 15ml green, 10ml blood, 5ml pink (opposite of course during bloom) until you get to your desired number. just remember green-blood-pink (3-2-1) during veg and green-blood-pink (1-2-3) during bloom.
I use ML's with an oral syringe for small amts and measuring cup for larger amts. I also have a 1 gal pitcher (with measurements) which comes in handy if you want to measure exact gallons or liters.
This may sound a little intimidating at 1st, but within a very short time; it will become 2nd nature.
Don't forget some kind of cal-mag (I use gh cali-magic) very important bc their standard mix is woefully low in Ca & Mg
Also make sure and get some Hydroguard.
When mixing always put the **calmag in 1st, mix well, then add the rest, stirring well between each addition (**if using silica, mix it 1st, very well, then calmag etc...)
If any of this doesn't make sense, lemme know and I'll try and clarify
