The flowering stage is greatly variated by strain. Indicas usually take around 8 weeks or so. Sativa take longer, so prolly around 10-14 weeks. Harvesting your crop at the right time is VERY important. It also depends on what kind of high you like. If you want a really strong couch lock high, you'll harvest when most of the Trichs are Amber. If you want a really hyper high, and less body, then you'll want to harvest when they're prolly 50 percent amber and 50 percent cloudy. Viewing the trichs is usually done with a hand held microscope. It needs to be at least 30 x power. There is a hand held 60x - 100x hand held microscope at radio shack for 10 dollars. I'll post a link to another thread attachment that will better help your understanding of Trichs.