You want to be ready to harvest in a week tops I don't know how long you need to flush (soil/hydro/nft) but be ready in a week. If in 4-7 days or so no new growth be it white flowers or sacs, cut at weeks end. A lot of strains especially 45 day strains will ripen early, then go through another growth spert a 5-7 days later. From the looks of that plants growth type if it doesn't start to swell or produce resin in that 4-5 days it won't, and next time you'll cut earlier. How much your plants are drinking/eating is a good indicator of what they're doing. If they are feeding then they will be adding density even if you don't see it. I would also recommend weighing individual plants, then compare next time when cut earlier. The weight test is a good way of fine tuning your days. You could also do like Smoke said if your hard up.
You didn't say where the amber tric's were on the plant, but in most cases the tops will mature faster than the rest. This will be most aparent with overhead artificial lighting. I will usually flush, cut tops, then feed and see how the bottoms respond. I'm in Hydro so I can flush quickly though. Also do screen or sog, can't rell tell if there's a canopy under cola in pic, but this method works extremely well will that kind of setup.