You can't really go by estimated times. The breeders or googles estimated flower time is always a couple to several weeks off. That's a high selling point on seeds, you know if they list a shorter flower time than others. I haven't grown a photo period or autoflower that's done in under 12 weeks. You just have to grow, as with almost every aspect of growing cannabis with experience comes an understanding of what's going on. By looking at the bud and trichomes you can guesstimate how long you have left. First few times it's just a hit and miss guess. After that you'll be able to pin point when you are about 2 weeks out and can cut back or stop nutrients. Nothing wrong with feeding until harvest, relax don't sweat it. It'll come more naturally with each grow