That sounds about right. My best overall results have been with a 2.5 week flush. Ideally if possible, I try to sharply taper down my feedings to where I'm feeding nothing but B-52 (B-complexes with Fulvic & Humic) and molasses (NPK and ATP building starches) for 10 days, and then only water for the last 7 days before chop. It's all a compromise - but I like that the plant is getting nutrition and starch till just a week before chop - and that the finished product has no undesirable tastes or burning attributes.
I also have had my battles with fungus gnats. I don't worry about them any longer, and I don't spray anything on the plants. What I changed -- my pots, what was in them, on top of them, and how I fed/watered. I switched to fabric pots (no holes to hide and breed in), and use quite a bit of perlite in my mix (top soil stays dry, air roots do better too), and I don't feed until the pot is almost dry (very light). If there are more than a half dozen of any type of pest, I add a light layer of Diamaceous Earth on top, and this will kill any hatchlings. This method has kept me free of gnats for almost 2 yrs perpetual, so hopefully there is some good info there. I wish DonP was still around, I copied his watering style - he was a great source of info. Anyway, loving your ladies - I'm betting that they fill out nicely.
Edit: I also use a clearing agent (Florikleen) when I stop feeding base nutes & supplements.
