Hi mate 8 weeks is the minimum for properly matured buds if you want the trichomes to be fully opaque with a few amber. This will give you the full effect the breeders were intending you get when marketing their seeds. I would not flush until the trichomes are at that stage then flush for 2-7 days and harvest . Hope this helps 😀

If your 30% milky your not ready. For Indica the ideal is %100 milky or close to it pending weather for outside. For Sativa 80% milky 20% amber. Keep an eye on this and when your gettin real close start your flush. And yes sometimes breeds are slightly off on the time. Good luck!