As far as the FF feeding goes, they ARE ready for nutes.
Use 1 teaspoon of Grow Big, and 1 Tablespoon of Big Bloom for the next 1-2 weeks. From that point until you flower them, increase the Grow Big to 2 teaspoons and the Big Bloom to 2 tablespoons. I throw in a quarter-teaspoon of Superthrive as well, and they love it.
Every 3rd watering just use plain distilled water with 1 tablespoon of Big Bloom as a buffer.
Ph your water before feeding. You'll be needing to raise your Ph with some Ph UP everytime basically as nutes drop your Ph big time. A good Ph pen is about $100.00, and is one of the first 'necessities' that you must have. You should have a small amount of Ph Down on hand too incase you raise the Ph too high.
If you see the tips of the leaves start to brown, or the plants get crazy dark green then back off the nutes and just give plain distilled water with 1 tablespoon of Big Bloom until they start to lighten up again. Eventually you'll develop a 'feel' for plants and you'll know what to give them based on their appearance rather than a feeding shedule which is more of a general guide. This, however, only comes with experience.